Quote:

71 360 manifolds were a completley different animal than the HP 340 manifolds.




No, not exactly true, the 3418623 RH side and 3418621 LH were the same for (some) 71 360 C-body's and all 71 340 B&E body cars.

The 71 A-body 340 used 2863553 on the LH side and 3418623 on the RH side.

The castings you listed above (351) are unique to C-body but I don't think 3418823 is a good number, I'll bet it's 3418623?.