What Move did Black Play?


Here is another game from the US Correspondence Championship.
Find the winning plan... Black to move

Quite interesting might be something like 1...b5 2.cb5 Bxb5 3.c4 (otherwise black wins exchange on f1) Rd4 4.Qc3 Re2!? 5.cb5 Ne4 6.Qa5 Nd2
If white takes Bxd2 then after Rdxd2 black has two rooks at 2nd rank - but it is not clear if that is worth a Bishop

dzikus you are somewhat close to the right answer. but the right answer is not so easy. Dave Taylor vs James Bovay 1988 7th US Championship