383 on ABody BB KFRAME?

I am not an expert on this, but I have no idea why Chrysler would have made a different motor mount for the M-code barracudas and darts. I put a 440+6 in my 383-S fastback and used the original 383 mount. I really doubt they are different.

We have two 440s, one 69 block and one 70. Neither has the bosses so I would suspect that's why they needed a different mount.