Providing your kickdown linkage is installed and hooked up, you might try this... Hold the kick down lever on the trans still, (all the way to the back of the trans in its travel). Loosen the kickdown rod locking screw until the kickdown rod will slide free. While holding the lever, move the rod towards the front of the truck, (Essentially lengthening the stroke), in 1/8" increments until your shifit points are where you want them.
It's a trial and error type of adjustment, but generally produces good results. If you go too far, the transmission will hang in one gear and will shift erratically. If this happens then you know you have to back it off about an 1/8" and try it again. This adjustment raises the line and governor pressure, which both are responsible for how hard and when your transmission shifts.
Good luck!
Dave
