Can anyone tell me what the proper scheduled maintanence is on B3 drives. I just bought a 2006 repo with 64 hours and no records. Should the drives be pulled now? How often normally? Thanks!

Merc reccomend service every 100 hours or annually, whichever is first. Many folks (including me) service every 50 hours. If it was me, I'd do it on any new-to-me boat, especially a repro. Oil is cheap.

Service includes many checks, but the big ones are:
Gear oil, check u-joints & gimbal bearing, check alignment, grease splines / coupler. Also check the anodes & Mercathode unit(s) - especially if moored for long periods in water, or operated in salt/brackish. BIII are known for corrosion (lots of stainless attached to aluminum).