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Discussion Starter · #1 ·
I'm thinking ahead on my 1975 RC Resto-Mod which will be getting a Cummins Re-power and was wondering if anyone has used the dash and steering column from a 1st Gen Cummins truck in an RC.

I don't have the donor yet but obviously will be looking for up to a 1993. I found this topic https://ramchargercentral.com/parts-compatibility-and-interchange-discussion/89-dash-into-77/msg3240577/#msg3240577 which suggests its possible but was wondering if anyone, including @SuperBurban or @dodgefred had any more information they could/would add to the process. It looks like dodgefred cut the firewall out of the later model rig and welded it into the older rig. Curious about the details of that.

It appeals to me also that if I did this I could also include power windows and locks into my 75.

Experience, thoughts, advice?

Thanks,

TXPower
 

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2nd Gen usually refers to a '94-'01 BR series Ram, which are a very different design.  I do know that someone was working on this swap some time ago, but I don't know if it as ever completed.  Your title may be a typo, but I figured I would clarify in any case. 

Any '72-'93 dash is an easy swap as the cab is basically the same.  The bulkhead, heater box and other details changed over the years so modifying the firewall may be necessary, but that swap has been done several times successfully.
 

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Discussion Starter · #3 ·
Elwenil said:
2nd Gen usually refers to a '94-'01 BR series Ram, which are a very different design. I do know that someone was working on this swap some time ago, but I don't know if it as ever completed. Your title may be a typo, but I figured I would clarify in any case.

Any '72-'93 dash is an easy swap as the cab is basically the same. The bulkhead, heater box and other details changed over the years so modifying the firewall may be necessary, but that swap has been done several times successfully.
Elwenil, thanks for the response.
I think you are right, I mis-titled my post.

I did mean to ask, could a dash from a 1st Gen Diesel Pickup be retrofitted into my 75 RC. It seams you are indicating the RC and PU dash, heat/ac ducting, wiring harness are pretty similar year model to year model up to 93. Right?

Any thoughts on whether modifying the firewall on my RC or removing the firewall from the donor and welding it into my RC would be less/more difficult and yield a better end result?

Thanks,

TXPower
 

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Yes, the dash should swap with no huge issues, but there are a lot of details to tidy up to make it work.  In my opinion, swapping the whole firewall panel would definitely look cleaner unless you want to do body work on the firewall to smooth it out.  Well, at least I probably would need a lot of body work if I just cut out and replaced bits and pieces and welded them in, lol.  But drilling out the spot welds and swapping the whole panel would be cleaner, possibly the same amount of work in the long run and would set you up for all the heat and A/C stuff as well as the wiring from the newer dash, steering column, etc.  It all depends on what you want in the end.  If you don't have A/C or are not concerned about all the vents, you could probably get by with the old heater box and make the two work together.  The wiring could also be spliced, though the later bulkhead is a much better design than the earlier versions.  It all depends on how comfortable you are trying to make things spliced together that were designed a decade or more apart.  But the dash itself is a pretty simple swap.  If I recall you have to change something about the anchors on the sides of the dash where they bolt near the door hinge area, but everything else should fit the shape of the cab pretty well.

Also keep in mind you have to pull the windshield to get the dash out as they have screws under the windshield gasket.  It's possible to get them out by cutting the gasket or, if it's new and pliable enough, bend it up to get to the screws.  I always just pop it out to pull a dash as it's not worth the fight to me and if the gasket is stiff, it probably needs replacing anyway.  Just my .02
 

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I have an 86 dash in my 78RC. As been discussed, the firewall is the big speedbump in the process. The passenger side, is to get the heater, or heater/AC unit to fit in place. The drivers side is hole for the firewall junction box.

6 of 1, and a 1/2 dozen of the other. The wiring that goes  with the dash, has a different junction box, swap that, then you have the under dash and rear end wires to think about.

Some have said they could swap the dash, without removing the windshield, or cutting the gasket. I do not see how. as the screws are angled up towards the glass. I cut triangles out of the gasket, as I will be swapping the windshield down the road, just did not want to leave it wide open until then.

The 80's steering column fits, but not great. The bracket at the dash, is almost flat across in the 70's body, and more U shaped in the 80's. So the 80's column, does not fit nicely in to the recess. And you end up with the steering wheel sitting lower (towards the seat, not towards the firewall). Thats on my list to modify the bracket.

Don't know how far you are going. I also used the 86 engine, and wiring. Which gave me the issue of which wiper motor to use. I used the 86. 2 of the 3 bolt holes lined up, and just had to drill, and weld a nut in for the third. Of course, that was before I swapped in the power brake booster. The smaller 3/4 ton booster is a tight fit against the wiper motor. There is no way a 1/2 ton booster would work.

Thats all I can remember right off, If I think of something I missed, I'll post it.
 

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Discussion Starter · #6 ·
Elwenil said:
Yes, the dash should swap with no huge issues, but there are a lot of details to tidy up to make it work. In my opinion, swapping the whole firewall panel would definitely look cleaner unless you want to do body work on the firewall to smooth it out. Well, at least I probably would need a lot of body work if I just cut out and replaced bits and pieces and welded them in, lol. But drilling out the spot welds and swapping the whole panel would be cleaner, possibly the same amount of work in the long run and would set you up for all the heat and A/C stuff as well as the wiring from the newer dash, steering column, etc. It all depends on what you want in the end. If you don't have A/C or are not concerned about all the vents, you could probably get by with the old heater box and make the two work together. The wiring could also be spliced, though the later bulkhead is a much better design than the earlier versions. It all depends on how comfortable you are trying to make things spliced together that were designed a decade or more apart. But the dash itself is a pretty simple swap. If I recall you have to change something about the anchors on the sides of the dash where they bolt near the door hinge area, but everything else should fit the shape of the cab pretty well.

Also keep in mind you have to pull the windshield to get the dash out as they have screws under the windshield gasket. It's possible to get them out by cutting the gasket or, if it's new and pliable enough, bend it up to get to the screws. I always just pop it out to pull a dash as it's not worth the fight to me and if the gasket is stiff, it probably needs replacing anyway. Just my .02
This is very helpful, just the information I was looking for, thanks.

I have this thing stripped and am doing floorpan repairs right now. Next, I'll do my rear quarter panels and a little repair to the bed area. After that, once I find a donor truck, I think I'll go ahead and pull the firewall from the donor and weld it in to my RC and use everything I can from the donor truck.

Thanks for the info and input,

TXPower
 

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I've done just a dash and heater box swap and if  do it again,  I'll do the whole firewall and steering column mount.
It roughs in ok, but lots of details make it a pain to do just the dash.

But I don't think I'd do it again anyway.  Its much easier to just modify the older dash to work with the diesel drivetrain
 

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Discussion Starter · #8 ·
Ruderunner said:
I've done just a dash and heater box swap and if do it again, I'll do the whole firewall and steering column mount.
It roughs in ok, but lots of details make it a pain to do just the dash.

But I don't think I'd do it again anyway. Its much easier to just modify the older dash to work with the diesel drivetrain
Ruderunner, can you provide a little more detail on your comment that it's easier to modify the older dash to work with the diesel drivetrain?

What specific issues did you run into with your build in this area?

When I stripped this thing the original wiring was scary looking. Brittle and a fire hazard. What can you tell me about how you handled your wiring?

Can you provide any details on how you retrofitted the dash and heater box into your rig, fitment, sealing it up, ducting, etc?

Are you non-A/C?

Did you start a thread on your build, any pics?

My plan right now is to take advantage of the donor wiring as much as possible, which ultimately gives me more options like power windows etc.

Thx,

TXPower
 

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To be clear,  I didn't do a diesel swap,  I swapped an 83 dash and harness into my 80 due to a wiring fire that destroyed the dash.

But, to get the diesel into the older trucks really only needs the charging system upgraded which can be done completely underhood except for bypassing the ammeter. Really on the first gen diesel trucks the most significant thing the computer and various sensors are needed for is to control overdrive.  But even that can be done with switches,  either toggle or pressure or both.

Indeed,  you can power the fuel solenoid off the existing ignition wires, your existing voltage regulator will be fine with the diesel alternator,  the existing guage sensors can be adapted easily with pipe fittings.

Keep in mind that the Cummins can be run completely free of electricity.

I was non ac and stayed that way.  I didn't add power windows or any options.

Getting to specifics on what problems I ran into,

Starting with the firewall itself,  the opening for the bulkhead connectors changed size,  shape and location several times over the years.  The parking brake assembly was redesigned but I can't remember what I did about it iirc there's an interference,  the steering column location and angle changed a bit which creates a problem with lining up the dash to the bracket,  there's a bracket welded to the newer firewall that supports the center of the newer dashboard,  surprisingly the 83 heater box bolted right up with maybe drilling on extra hole but the opening for the cowl vent is slightly off.

Speaking of kick panels,  aside from the cowl vent and parking brake,  there's the lack of a reinforced place for the lower corners of the dash to bolt to.

HVAC problems center mainly around the ductwork early trucks used flexible hoses to send air to the right places,  newer have molded ducts its best if the box, ducts and dash are a matched set. Controls and wiring vary by year and option.

For wiring,  I used the dash and underhood stuff from an 83 gas engine truck,  this matched reasonably well with the vehicle.  As stated the bulkhead connectors doesn't fit quite right.  I did have to splice wires for the front marker and turn signals. The connectors for rear lights are different,  I don't recall if I just swapped terminals between connectors or spliced everything. Not, both trucks were basic models.

More recently I was going to swap harnesses between a stripper 83 and an optioned up 87. Plan was to eliminate the ac and cruise control from the 87 (both systems were damaged beyond reasonable repair and I had a standard column and heater box from the 83)  In the end I repaired the 87 harness and eliminated the extra wires, changed out the column and heater box and control to match the non ac stuff.  The power window wiring was the reason for reusing the 87 harness.

Realistically the only thing that lined up without hassle are the 5 screws at the bottom of the windshield.

In your case the ratty wiring and desire to add options makes the firewall swap more sensible,  use all of the diesel harness,  don't bother trying to mix things up.  Worst case you might have to splice connectors for some lights.
 

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Discussion Starter · #10 ·
Ruderunner said:
To be clear, I didn't do a diesel swap, I swapped an 83 dash and harness into my 80 due to a wiring fire that destroyed the dash.

But, to get the diesel into the older trucks really only needs the charging system upgraded which can be done completely underhood except for bypassing the ammeter. Really on the first gen diesel trucks the most significant thing the computer and various sensors are needed for is to control overdrive. But even that can be done with switches, either toggle or pressure or both.

Indeed, you can power the fuel solenoid off the existing ignition wires, your existing voltage regulator will be fine with the diesel alternator, the existing guage sensors can be adapted easily with pipe fittings.

Keep in mind that the Cummins can be run completely free of electricity.

I was non ac and stayed that way. I didn't add power windows or any options.

Getting to specifics on what problems I ran into,

Starting with the firewall itself, the opening for the bulkhead connectors changed size, shape and location several times over the years. The parking brake assembly was redesigned but I can't remember what I did about it iirc there's an interference, the steering column location and angle changed a bit which creates a problem with lining up the dash to the bracket, there's a bracket welded to the newer firewall that supports the center of the newer dashboard, surprisingly the 83 heater box bolted right up with maybe drilling on extra hole but the opening for the cowl vent is slightly off.

Speaking of kick panels, aside from the cowl vent and parking brake, there's the lack of a reinforced place for the lower corners of the dash to bolt to.

HVAC problems center mainly around the ductwork early trucks used flexible hoses to send air to the right places, newer have molded ducts its best if the box, ducts and dash are a matched set. Controls and wiring vary by year and option.

For wiring, I used the dash and underhood stuff from an 83 gas engine truck, this matched reasonably well with the vehicle. As stated the bulkhead connectors doesn't fit quite right. I did have to splice wires for the front marker and turn signals. The connectors for rear lights are different, I don't recall if I just swapped terminals between connectors or spliced everything. Not, both trucks were basic models.

More recently I was going to swap harnesses between a stripper 83 and an optioned up 87. Plan was to eliminate the ac and cruise control from the 87 (both systems were damaged beyond reasonable repair and I had a standard column and heater box from the 83) In the end I repaired the 87 harness and eliminated the extra wires, changed out the column and heater box and control to match the non ac stuff. The power window wiring was the reason for reusing the 87 harness.

Realistically the only thing that lined up without hassle are the 5 screws at the bottom of the windshield.

In your case the ratty wiring and desire to add options makes the firewall swap more sensible, use all of the diesel harness, don't bother trying to mix things up. Worst case you might have to splice connectors for some lights.
Great info, thanks for the response Ruderunner.

TXPower
 
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