IIRC, the housing on the '67-'72 mounts the same as the '65/66. However, the '71/72 is about 2" wider than the earlier 6 lug axles, so the shafts do not interchange, or at least not going 5 lug to 6. I have heard of guys swapping the 5 lug axles into the 6 lug housing, after getting the shortened, to change to 5 lug.
