The Stovebolt Site Forums The Shop Area Driveline 4 wheel drive swap

Can someone tell me the easiest way to convert a 71 c20 (3/4 ton) from a 2 wheel dr. to a 4 wheel drive and what components work best. Would like to be able to bolt up the 4 wheel system and not have to make any major alterations if possible.

Starting with a K20 frame and axles might be the easiest. Even if you remove the existing front suspension is the 2wd frame the same as the 4x4 version?

I don't know if the frames are the same.
What years K20 frame and or suspension r u talking about? Isn't there a 70-80 4-wheel original drive train that will swap in?

You're looking at a lot of work. The suspension systems are completely different, with major differences in the frame for not only the suspension mounting points, but also crossmember differences for the transfer case. For using the entire chassis from a later truck, you will be looking at wheelbase issues (the '73 and later trucks are longer).

Finding a 67-72 4wd frame is the way to go, finding a 71-72 is best, disc brakes, better gear ratios too. Buying or fabing spring hangers for your frame can be a pita, although can be done. I see it this way, you have a separate frame to build from the axles up, frame, paint, brake work, ect, at your leisure. Your 2wd can still be driven until you are completely ready to do the swap. They come up from time to time here in the salted northeast, I would assume you can find some in that nice dry desert you have.

Along the same lines as Grigg, Longbox and Alltruck: Three ways to go. Should be able to find a K20 complete truck. There is a 1972 in Tucson for $4200. Faster than finding a frame and you can test the drivetrain/mechanicals somewhat. Swap bodies and frames and resell. When I did it to a 56GMC Carryall I had the donor (80 4X4 suburban) frame sitting right next to the 56 frame. Made it a whole lot easier to plan. In my case, I used the 56 frame and fabbed in the 4X4 stuff. (axles, springs, 205 Xfer case, 454 BBC. TH350, steering, etc.) MUCH work, but fun at the time figuring it all out. Whatever you do, it's not going to be a bolt on, easy deal. You've got wiring, plumbing, shifters, linkages, motor/tranny/Xfer compatability, axle ratios match and unknowns...Best way is sell your truck and buy another
Yes, I took off two bodies, put onto two body dollies. It takes a bit of room and preplanning to roll everything around.
When you say "swap in", we don't know what you are thinking. Swap front axle and add xfer case? As said, converting A Arm to leaf is possible maybe, but it's all Big Boy fab stuff. Cutting, de-riveting, welding, measuring, plumb bob.... getting the front axle in same place as old axle which locates the xfer case which locates the tranny which locates the motor.......I would think 2WD and 4WD frames are the same for 71. Not the holes and brackets, but the frame rails/shape/length/bumper mounts, gas tank mount, Ebrake, body mounts, bed mounts. You would be de-riveting/unbolting the front suspension completely, de-rivet the donor frame spring hangers and shackle mounts and wheel the whole thing under the front of the 2WD and so on....
When you talk mixing years up to 80 you are talking some different xfer case choices possibly. You want NP205. Pre 71 you may run into closed knuckle front, you don't want that. (1969 and back) 1970 open Knuckle but maybe no disc.

So do you know if the 67 and 71 frames are the same? If not what changes would I have to make to make a swap? What type of axles and transfer case would the 67 have? I have a friend who has a complete 67 chassis including a engine and trans. Appreciate the help. Dave

As for me, I do not know. Can you not measure the friends frame, etc? Or is it out of state? I would not buy anything without measuring myself or factory drawings.