I agree with Dually, it's a pita to put the cab and body over on the newer frame. You have to cut off the body mounts, none of them line up. The bed and cab set at a different height, front frame horns are different for mounting the bumper, you will either have to move the axle or move the bed back from the cab and have a bigger gap to get it centered. Where if you use the 2wd frame all you have to do is change the suspension, and your crossmembers will bolt in! My 70 in setting on an 81 frame and I absoultely hate it, I have a 2wd 70 frame that I am going to put it on, soooo much easier!!!!
