Would be to me, although just this scenario came to light last year. There is a possibility that a customer could have ordered the HD 3 speed as an option on the Muncie-mandated Z cars - after all, you could even get them behind 375 horse BB's. Never say never, I would guess.
This one appears to be a Muncie, 3.03:1 first gear ratio coded, but the maincase is not listed as a passenger car application (hence the threaded flanges make sense). Anybody have any more info on it ?