340 Hi-Po manifold stamping

'68 Dart; Parts manual calls for 2863545 and 2863552 for exhaust manifolds. It seems like I read that those numbers were later revised to 2863549 and 2863553. Are these identical parts with just a part number stamping changed? I don't want to spend an arm and a leg on manifolds with one stamping or the other and then find that the clearances aren't right because of some subtle change. I want to use standard oil filter, starter, power steering, etc.