Any difference in 71, 72 & 73 buckets?

[Fitz73Chrgr]

I'm going to look at a parts car this weekend.  The guy says it's a 71, but from the vague pictures I suspect it may be a 72. 

Are there any differences in the way a 71 or 72 bucket seat mounts?  Would I have any problems putting them in my 73?

Is the seat frame the same in that I would be able to reupholster the seats with 73 covers?

Thanks in advance!

[Nacho-RT74]

71s got a change in mid year production.

If is the second half, frame and rear panel are the same with 72s ( and lates ).

However foam and covers remain the same all 71 production... 72/74 got same foam and covers however 74s got a diff grain vinyl pattern on outer section