I hope this info will be helpful to some folks, it was for me. I'm swapping axles in the 62 4wd burban that I have, and was looking for some axles that will bolt in. The front is easy, any 73 and up will bolt in. But the rear, only Gm 1 tons will bolt in, with the 40 1/2" spring pad width. Well, after some searching, measuring, and some head scratching, I found out that 79 and older Ford, HEAVY DUTY 3/4 or maybe 1 ton have the same spring pad width. These are Dana 60s rears, I don't know about the Dana 70s, the junkyard didn't have any. I measured regular 3/4 tons, and they have a wider pad width. So, if anybody is swapping axles on a 60-66 4x4, there is an axle besides the heavy ass 14 bolt that will bolt in. I will get some pics when I can. Hope this helps someone!!!!