[Mr70]

Stefano
Take this with a grain of salt as my records are not as complete as others.
I'm finding the Muncie M-20 #3870372 was installed behind the 1966-67 396cid & 427cid vehicles only.
It also shows when the 1966 Passenger series got a 327cid,it got Muncie M-20 #3884603 (Not used behind L-79).
A friend of mine who owns a 1967 327cid Passenger series has an M-20 w/#3916108 tag on it.
I'm sure crash could help narrow this down some more.