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[Bushwacker]

Yes, you want to use 4200 or Life Caulk on something you want to remove later, like engine mount bolts. For sealing something like the inner liner/transom gap that wants to be a permanent seal, I would use 5200 except that it didn't exist in 1975, so I used the next best thing which was Life Caulk, which remains flexible and doesn't crack.

Looks like you already have a bracket on the SeaCraft. When you rerig it, if you run the rigging down thru the flotation tank like Don Herman recommends (see pic below), you'll have a neater installation that doesn't clutter up the swim platform as much. For a 30" bracket setback you need to allow for about 6' of length in the hoses and cables to run thru the rigging tubes. Don used to sell a rigging kit for about $40 in 2006 when I rigged mine. I also added a strip of rub rail to the edges of the bracket because it can get dinged when you're docking around pilings, etc.