67 to 71
There were two different axle types available in 67, the normal 8.2" used in the 64-67 cars and as a mid-year intro the Type O used in 67-70. The 8.2" will be narrower, the Type O will be the same width as all the 68-72 axles. I have a Type O that I personally pulled from a 67 parts car and it's the same as the 68-70 Type O axles.
The 68-72 cars came with a variety of axles also, the Chevy 12 bolt, Chevy corporate 10-bolt, and Olds Type O axles. The "12 bolt" Type O was actually available from mid 67 through 1970. Interestingly, the 67 housing is the same width as the 68-72 housings instead of the other narrower 64-67 housings. There 71-72 Cutlii used an axle that was called "Type O" but this is actually a corporate 10 bolt 8.5" center section with Olds-style axle retention instead of the C-clips.
Anyway, that's a roundabout answer to the original question. Yes, a 67 axle will fit a 71. If it's a Type O, it will be the same width. If it's an earlier axle it will be 1.5" narrower. Driveshaft length may also vary slightly.


