Will a 1981 "pre alpha" 165 outdrive fit on a 1970 bell housing?

[Pgh70Twain]

Looking for someone who knows the "way back in time" stuff; my 1970 Mercruiser 165HP needs a new outdrive. I could get one off a 1981 (exact same motor, and outdrive pics look the same (externally).
I read that the 1970 & 1971 prealpha drives were the same but in 1972 some design changes were made. Just need to know if a 1981 pre-alpha outdrive will match up on the 1970 bell housing and work without any mods. (gaskets, o-rings, yoke length, etc.)
Thanks !

 

[achris]

The 1981 MC1 drive (no such thing as a 'pre-alpha') should fit straight onto a 1970 MC1 transom housing.

Chris......

 

[kenny nunez]

Be sure that the thrust pads on the drives are the same width. I know that sometime around 67-68 was the the changeover to the wider bolt pattern and thrust pads. Use the gasket to check if the holes line up. Some boat manufactures sometimes had old stock so they installed it in a later boat.