I ordered National #8660S from Rockauto (who listed it for 70 Valiant w/7-1/4" rear)

I received Auto Pride #13992-AP.

Sealed Power, Ford, Mack & Freightliner have some variation of 13992 as a x-ref for National 8660S

I assume the part matches what I ordered, but I'm not sure it matches the application. Only A-bodies I see anything saying these #s fit, are 73-up.

The 7-1/4" rears change w/the bolt pattern in '73. Does the seal change too?

What is the right number?

Please advise?