Seat frame differences

[Matt68]

so, I purchased new foam and seat covers for my 1973 'Cuda. Problem is, the shop says my current seats are 1971 and the foam and covers are not compatible. Anyone know the interchange ability between the years?
TIA
Also, can anyone decode this frame tag?

 

[Mr Cuda]

Well, here goes.
70, early 71.
71- mid year 72.
Late 72,73-4
B mirrors E thru 72. Late 72B has a change on the back by removing springs and using a foam insert to fill the full void.
I believe 73-4E are the same as 73-4 and up A body.

 

[Matt68]

Well, here goes.
70, early 71.
71- mid year 72.
Late 72,73-4
B mirrors E thru 72. Late 72B has a change on the back by removing springs and using a foam insert to fill the full void.
I believe 73-4E are the same as 73-4 and up A body.

Damn