Will A '98-00 Lower Bolt Up To A '91 Upper?

I recall this as being the year they changed the lubrication of the B1. If your 91' upper has the oil passage, it will fit. If not, it won't,

I've Heard Of Tapping And Plugging The Oiler Hole To Convert. But Have Heard Pros/cons- Any Opinions

If you need the older version. I have a whole drive just redone like new for less than a lower. Lmk

The link below will help give you an idea of what to look for with this question.

http://www.boatfix.com/merc/Bullet/91/91_20.pdf

If you have an old style upper with no oil passage you can put a newer lower with the oil hole on. The newer lower has to have the oil passage closed off so no water gets into it. Tap it and screw plug in or 4200 or silicone, anything to seal water out.