Re: info on alpha one
You may want to check, but I think that SN is actually 0
D537618 instead of 00.
If that is the case, it is an Alpha I Gen II outdrive.
You need Service manual #14 for the outdrive, and Service manual #13 for the Engine.
You can download them both from the link below.
http://www.boatfix.com/merc/Servmanl/srvcovr.pdf
As far as maintenance goes, if you don't have any history or knowledge of the maintenance done on the engine and outdrive, I would suggest you start from scratch, do a full tuneup, oil and filter change, fuel filter change.
On the drive, change the gear lube, while you have it drained, you should replace the raw water pump impeller.
I would also replace the ujoint bellows. A hole in it will allow water into the outdrive, and the ujoints and gimbal bearing. Might want to look on ebay for an alignment bar also. You need to check the alignment at least once a year.
You can also download a 2001 owners manual at the link below.
http://www.boatfix.com/merc/Servmanl/srvcovr.pdf
While newer, the engine and drive is almost identical to todays model.
Chris is right about the SN, but one thing, the 0B number would be for a 1986 drive on a Mercruiser 165 (470) which is also the wrong gear ratio.
The 0D number goes to a 91 Bayliner with a 3.0L ............. Like you have.