12 Bolt axle I'm not sure, but if you're talking about the ENTIRE rear end axle housing, I think it will fit. I installed a '72 in a '71 truck and it was a perfect swap. If you have a good 12 bolt/6 lug now, you can replace just the axle's with 5 lug aftermarket axle's? If you do the swap, measure your existing housing width from backing plate to backing plate (or axle face to axle face). If this matches, measure the points on the housing where the spring centers mount. Compare these with the same on the new housing. If they match, I think you're OK to do the swap! Good luck.
Thanks for the reply, I was hoping to just change the axle shafts as the diff has an eaton posi unit. I am converting front to 5 lug disc, as it is easier to find and with more options on rim choice
According to a website ordering catalog I've used, all 1963 thru 1972, 6 lug & 5 lug axels are 30 spline, however, they sell '63 thru '69 5&6 lug seperate from '71-'72. This indicates the 71/72 must have a longer or shorter spline or the overall axel length is different? They all list for about $279 a pair. If your intrested, look at www.CLASSIC PARTS OF AMERICA.com, they have a Q&A you can ask their technical staff specific questions on. Good luck!
