Y-Pipe Help!?!?!?

[BackinBlack]

Ok, long story short...own '99, wrecked truck, replaced frame, GM says frame is newer/different, and that I need a new Y pipe with the new frame. What is the difference? I know the transmission crossmember looks a little different, and the furthest rear exhaust hanger is different. How do I know which aftermarket exh. to buy?

Thanks,
Brandon