What numbers in the VIN define it as a macho on a 77 ramcharger ? Any input would be greatly appreciated.

there are no VIN numbers that tell you for sure on a macho ramcharger, just the under hood label and the remnants of decals on the body.

What do I look for on the under the hood label ?

I am not 100% for sure on a 77, but it might say something like model conversion, or special tape stripe, or macho decal.......but once again, I am not sure, I had a black 77 macho ramcharger a few years back, and it was missing the underhood label IIRC...