Hello all, I have a 1994 Laser 17 foot bass boat. Fiberglass. 120HP Johnson OB. The trolling motor is dead. It's an OMC 12/24 volt. I have no idea what size it is to buy a replacement. How can I either tell what the old one is or figure out how strong of a new one to buy? I will have 2 deep cycle batteries already from the old motor to use. I am limited on $$ so I don't want to buy a 70# if a 50# will be fine. Also, this may seem like a dumb question, but how is the shaft length measured? Is it just the actual shaft itself? Or from the top of the whole unit to the bottom the skegg? Just measuring the shaft, mine is 43", if you just go off of the shaft length would a 42" be ok? Thanks!