They started changing from the 1 drive to the alpha 1 in 1984/1985 time
frame. It's hard to say what you have without splitting the gear cases. The
non alpha drives had a pin sticking out of the top of the vertical
driveshaft.
JIMinFL

"burgs" wrote in message
...
I have a leg off the back of a mercruiser 470 motor and the only serial
number I have been able to find (so far) is 5931945 with a large "4" about
an inch to the right and up about an inch higher than the serial number
off
the drive unit. This number does not seem to come up on Alpha one serial
numbers that I can find, and a manual lists it as a 470R sterndrive. I am
now toatlly confused between Alpha one, 470 R and model 1 drives Is this
the same as an alpha one drive? The reason I ask is because I have the
opportunity to replace my 470 motor with a motor set up for an Alpha one
drive but now I'm not sure that I have an Alpha one. The drive seems to
meet
the description for an early of model 1 alpha drive, but now I just don't
know!!

Where would I find other nos. on either the lower gearbox unit or maybe
gimal housing to check out this unit? The Bell housing unit seems to look
like the diagrams for the later model 1 due to the round shaped rubber
ring.

Any help would be appreciated.

KenW