904 Tranny pan New parts number?

Tried ordering a new transmission pan from the dealer using the parts numbers:
52118 779AB

Parts guy says the pan number changed and he was not positive if the parts were the same ones I wanted, but they appeared to be - anyone else encountered the changed parts numbers?

5211877AB has been changed to a 5211877AD pan $42.41

So, now I'm starting to wonder is the "D" for a deeper pan?

Thanks!