the 12bolt rears that were supplied in 64-72?

What I am wondering specifically is were there any differences in the "tabs or ears" that are on the top of the punkin across these years or were they all interchangeable?

Any information on this would be greatly appreciated. Thanks.

Regards,

Ears are the same and interchangeable I think, but I know the older are ones are 1" shorter. 67 and older are the short ones, 68 and newer were the wider ones. If I'm wrong I'm sure someone will correct me.

The center rearend castings are all the same.
The upper control arms are of a different length between the '67 & older and the '68 & newer A-bodies. As are the rearend tube lengths.

The 65's& 66's 12b rear's have the springs mounted with a bolt and plate.
'67 on up have a raised perch which the spring just "sits"on.
'67 rears are unique as they are narrow like the '65 & '66 rears but the perches are same as the 68 later [rasied].
I blew up my 10b back in the early '80's and put a '70 12b posi in.
about 9 years ago I put a "correct" '67 12b posi in.