I'm getting ready to replace my Bravo 1 lower with an IMCO shorty lower drive, I've been reading that this is a direct change nothing special is required to peform this change.

Any advice would be appreciated.

Nothing special is required. Its no different than removing and reinstalling the same lower. Just get a new upper to lower seal kit.

Don't forget the coupler
Fill the drive from the bottom to the vent. Plug vent and fill to reservoir

Watch out for the bolts holding upper anode plate are to long & will touch the Imco lower.

What about speedometer operation? The directions on mine said to plug the hole in the lower with a pipe thread plug. Will I have to go to a gps speedo? mine has always been dead nuts accurate.

You can go GPS or mount a speedo pick up pitot on the hull. I would switch to GPS.

thanks- I'm planning on going with GPS speedo, what about the longer bolt issue/ concern? Sounds like I should plan on getting shorter ones.

I have a new in the box Gaffrig digital speedo with recall and an antenna, white. $300

what size and what does it max out at?

The bolts that hold the cavitation plate anode on, stick through the plate about 1/4". The Imco lower will hit them and will cause the lower to not seat on the upper housing fully. Just remove the bolts and cut them off, or buy some SS bolts 1/4" shorter.. Easy fix, no worrys, unless you dont know about it and find leaks later..

Dick