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Discussion Starter · #1 ·
To start, I’ll give a little background. A few years ago I bought a 1979 trailduster without a motor or tranny. I started to swap a 1978 440 in it and got close but the motor and tranny we’re giving me issues so out they came. I got married and sold everything. Immediately regretted it and so I have now tracked down my old trailduster and am buying it back. It still doesn’t have a motor but the guy I am buying it from is including a 1986 360. I have a couple questions here. Will the 360 have enough power for my trailduster? I have 35’s and 4.56 gears. I hardly ever was able to drive it with the 440 before, but when I did, it seemed like a dog. Is the 86 360 going to be a fairly easy swap or will I have to deal with emissions and smog stuff? The truck came stock with a 360, so I may be better starting off anyways.  Thanks in advance.
 

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The 360 is ample to move your TD if it is healthy. The late 70's were not a great time for power numbers. New Cafe standards and oil fears of recent memory played a part. . In 86 the 360 made very similar power numbers as the newer magnum engine. ( Correct me if I am wrong) I think it will be fine. Will it be a crazy power house? No. Also if you keep those steep gears and a three speed trans you better run some tall tires.
 

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If fact the factory rated the 78 440 as very similar numbers as the 87 360. Within 5 or so if memory serves me. I'm not really a stats guy. Proper setup of final drive ratio I'm sure it will do what you want it too.
 

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Is your tranny set up for a small block or big block?  They don't interchange, remember that when making your decision unless you have full drivetrains for both.  Just things to keep in mind. 

Depends on what kind of money you want to spend.  Either motor will work fine, as Mechanized stated will either be a power house, no.  Will it move and be effective yes. 
If you start dumping money into things to make it better, their is no replacement for displacement.  But if it is going to be driven frequently you may want to think of gas prices too, (not a concern of mine).  ;D

Neil
 

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Discussion Starter · #5 ·
The 360 is coming with a transmission, and there’s currently no transmission in the truck, so I won’t have to worry about having a big block transmission and a small block motor. I am thinking I’ll just stick with the 360 since I’ll already have it, and I can’t find any 440’s near. The 360 may be a slightly easier install so it’s not a big deal. When I had the 440 in, I also had the NP203 behind it. Will this same transfer case work with the small block motor and transmission?  I’m unsure if any differences in output shaft lengths and what will fit in what transfer case.

The 35s are old and will need to be replaced before I can get it in the road. He is including a set of 37’s, but I’m thinking these may be too tall for my motor and heating set up. Thoughts on this?
 

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I wouldn't waste my time with a stock smog 440.
Like anything else stock... you can build them up with the proper balanced parts.
The key is parts that work well together.
A 360 is a good engine. The biggest problem with them is the same issue with a smog 440... way too low of compression. And a cam with very low lift.
With time, patience and the "lay away plan" you can slowly get the right parts and do it right- which ever way you decide to go.
Just don't sell your Trailduster again. ;D

And you can never have too much power!
 

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360 is fine if built right. You'll have plenty of satisfaction with one designed for torque.
 

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The NP203 will not mount to a '80-'93 transmission.
 

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Elwenil said:
The NP203 will not mount to a '80-'93 transmission.
Yep. It may be a good time to switch to the part time NP208 or NP241 transfer case if you plan to use that SB 727, or even better, A518 with overdrive. You could keep your full time axles and have shift on the fly 4x4.
 

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J10Mike said:
Yep. It may be a good time to switch to the part time NP208 or NP241 transfer case if you plan to use that SB 727, or even better, A518 with overdrive. You could keep your full time axles and have shift on the fly 4x4.
A NP 205 would be the best.
 

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Discussion Starter · #11 ·
I don’t think the trailduster will be leaving me again any time soon. I had a hell of a time finding this one time, I don’t plan on having to do it again.

My front axle has already been converted to part time with warn hubs. Granted, this may not be the best way to convert to part time, but it does the job for now.
 
Why doesn’t the NP203 bolt to the ‘80-93 transmission? Is it a bolt pattern issue or output shaft? This makes a bit more sense now because when I bought the trailduster, it originally had a small block 360 in it and only had a transmission in it. But when I put the 440 and tranny in, it wouldn’t bolt up or sit back far enough. Seemed the output shaft was too long so I used the transfer case that came with the 440.

Will the NP205, NP208, or NP241 all bolt to the 86 trans? Do they still use an extension housing? Should I anticipate having to move any crossmembers or getting driveshafts shortened or lengthened? The nice thing with the 440 drivetrain was everything sat right where it should. I used all stock holes for the motor and transfer case. Will the 86 with any combination of these three transfer cases be the same way? I think this is my biggest worry.

I’m not sure what trans or transfer case is coming with the motor yet, but I like to be prepared.
 

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laxjunkie said:
I don't think the trailduster will be leaving me again any time soon. I had a hell of a time finding this one time, I don't plan on having to do it again.

My front axle has already been converted to part time with warn hubs. Granted, this may not be the best way to convert to part time, but it does the job for now.

Why doesn't the NP203 bolt to the '80-93 transmission? Is it a bolt pattern issue or output shaft? This makes a bit more sense now because when I bought the trailduster, it originally had a small block 360 in it and only had a transmission in it. But when I put the 440 and tranny in, it wouldn't bolt up or sit back far enough. Seemed the output shaft was too long so I used the transfer case that came with the 440.

Will the NP205, NP208, or NP241 all bolt to the 86 trans? Do they still use an extension housing? Should I anticipate having to move any crossmembers or getting driveshafts shortened or lengthened? The nice thing with the 440 drivetrain was everything sat right where it should. I used all stock holes for the motor and transfer case. Will the 86 with any combination of these three transfer cases be the same way? I think this is my biggest worry.

I'm not sure what trans or transfer case is coming with the motor yet, but I like to be prepared.
I'd do the divorced 205. It is separated from the transmission.
And you can not hurt a 205... ever. They're made of granite. ;D
Yes you will have to redo the driveshafts. Plus add a short one between the transmission and the 205.
Not real cheap... but it will last forever.
 

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Yes, it's the bolt pattern difference. For auto transmissions, the NP203 will only bolt to a 74 thru 78 BB 727 and 74 thru 79 SB 727.
Like Kurt just mentioned, the NP205 is virtually indestructible. However, the 89 thru 93 CTD 23 spline married NP205 will bolt to the 727 and A518 as well as the NP208 (A518 with modification) and NP241.
The transmission cross member will not have to be relocated. Even if installing the A518 with overdrive, the cross member will not need to be moved. The transmission mount is the same distance front to mount as the 727.
As for drive shafts, the A518 is 5.5 inches longer than the 727. The NP208/NP241 both are 5.5 inches shorter than the NP203. If you install the A518 transmission, no modification for the rear drive shaft. The front drive shaft will need to be modified though. If keeping the 727, both drive shafts will probably have to be modified. The rear drive shaft for sure. The front drive shaft may be able to use a Superlift spacer in order to reach the front axle.

Mike 
 
 

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Discussion Starter · #14 ·
So there have been a few late 70’s trucks with 360’s in them. If I were to get one of these, I could most likely take the motor and trans and use my NP203?

This is all great info, I’m just exploring my options and see what’s available around. And personally, would like the simplicity of not having to get different transfer cases and then driveshafts when maybe there’s a motor and tranny I could just throw in instead.

Or are there any older transmission that would bolt up to the 86 360 AND my NP203? Meaning could I find a late 70’s small block transmission that will bolt to the 360 and use my Np203?
 

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If you are going automatic, your only choice for a 4WD that will mate with the NP203 is a 727 from a 4WD pickup from '75-'79 or a 727 from a 4WD Ramcharger/Trailduster from '74-'79.  The Ramchargers debuted with the full time 4WD system in '74, the pickups converted over the next year.

The issue with the NP203 and the later 727s and A518s is bolt pattern and output shaft length.  Even if you changed a '80-'93 727's tailshaft housing to the earlier version, the output shaft is still the wrong length.  But if you already have the axle converted to part time, then there is no reason to stick with the NP203.  Even if you do use the NP203, the front locking hubs become useless since you would need to leave them locked in all the time as the NP203 in stock configuration cannot be run without the front axle locked in.  Even if the hubs are locked in, if some prankster pulls the trick of trying to lock in your hubs for you, they will inadvertently unlock the hub which can allow the vehicle to roll away, even in park.  You can convert the NP203 to part time, but if you can just use a part time transfer case, there isn't much point in tearing one down to install a conversion kit when you can just pick up a part time case and transmission and go.
 

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Discussion Starter · #16 ·
Okay, I’m going to be honest...that confused me a little. I thought the point of having manual hubs with the full time NP203 was to basically make it part time and only have 4wd when the hubs are locked. So how can it not be run with unlocked hubs? And how does unlocking the hubs negate the fact that you are in park and have a rear driveshaft that should keep the truck from rolling away?

So far, it sounds like just finding another transfer case would be best, and just go ahead and get my current driveshafts shortened and lengthened. Which would beat the best route to go? I know the 205’s are known for being tough, but I also hardly see any for sale or at a decent price when I do. What about the 208 or 241? I’ll have to do some research on my own, but am pretty lost when it comes to transfer cases. Heck, I’m lost with anything.

Another option I think I may have is a 440 from a motor home. I realize that most, if not all, only came with 2 wheel drive transmissions.  Would it be difficult to convert a 2wd tranny to 4wd?
 

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The NP203 drives the front and rear driveshafts equally.  To allow for the speed differences in the axle during turns, it has an "open" differential in the transfer case, much like an axle with an open differential allows for the difference in speed between the inside and outside tires in turns.  Much like a rear axle with an open differential, if you raise one wheel, all the power will go to that wheel and you don't go anywhere.  With the NP203, if you disconnect the front axle from the equation, all the power will go to the front and the truck won't move and is actually free to roll downhill, similar to putting the truck in neutral.  In order for an open differential to work, you need similar resistance at all points, which in the case of a full time 4WD truck with open diffs in the axles, is all 4 tires.  The NP203 does have a "Loc" function, which essentially locks the center differential so that it operates more like a part time 4WD truck with 4WD engaged.  It uses pins in the differential to lock it in place, but using like this for daily driving can wear out the pins and break the differential.  So the NP203 must be converted to part time with a conversion kit or the front hubs must remain locked 24/7.  The conversion kits do have a few issues, mainly with lubricating the front output of the transfer case so it is recommended when using a converted NP203 to run it in 4WD once a month to ensure the front gets lube.

To convert a 2WD 727 to 4WD, you will need a 4WD 727 to get the output shaft and tail housing from.  Small block or big block doesn't matter.  You will have to completely dismantle both transmissions since the tailshaft is the last part out the front of the transmission, so it's a good time to do a rebuild in the process.
 

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Elwenil is so right on this 203 transfer case.  I learned the hardway regarding the transfer case driving equally.  I blew apart the auto front hubs on my 83 after putting in a full time 203 case w/tranny.  The front axle you could see sitting their spinning fast as hell with no movement in the truck.  If you put it in "loc" she would pull the rear wheels only.  That is the downside to the 203, limited year run and specific parts.  The 205 is the most desirable as everyone else has indicated on here.  One of the best things to ever come out of stock development.  They literally are indestructible. 

In my situation with the 203, put warn locking hubs in then the transmission went.  About a month later. 

I went ahead and swapped back to the 83 727 tranny and np208 to have a working truck again. 

Neil
 

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neil4224 said:
Elwenil is so right on this 203 transfer case. I learned the hardway regarding the transfer case driving equally. I blew apart the auto front hubs on my 83 after putting in a full time 203 case w/tranny. The front axle you could see sitting their spinning fast as hell with no movement in the truck. If you put it in "loc" she would pull the rear wheels only. That is the downside to the 203, limited year run and specific parts. The 205 is the most desirable as everyone else has indicated on here. One of the best things to ever come out of stock development. They literally are indestructible.

In my situation with the 203, put warn locking hubs in then the transmission went. About a month later.

I went ahead and swapped back to the 83 727 tranny and np208 to have a working truck again.

Neil
Nice explaining your experience there.
I only have experience with my 205 that came in my truck.
I didn't realize when I got my truck how lucky I was to have the 205 come stock with my truck.
Not to mention a divorced set up.
I love my '74! ;D
 

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Discussion Starter · #20 ·
Okay, thanks for the explanation. That makes a lot more sense now. Would I have been able to drive at all with the NP203 and hubs unlocked and the failure happen over time or would it have been impossible to move?  I was able to drive it with the 440, but maybe I didn’t have an NP203 with the 440 and didn’t realize it.

So what year transfer cases would bolt up to the 86 SB 360 and 727? I may just find a transfer case and get driveshafts modified to work.
 
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