Can anybody tell me what these 2 harmonic balancer casting #'s come back to? Both are wide, 8" dia.

3942533
3896966

Thanks

Sure, here goes:

3896966 = 1967-68 Camaro with 350 engine (8")

3942533 isnt in my book. My book is from 1977 and it's more likely that this number was changed before my book came out.