New Solenoid....car or Marine?
 

Changing out (old for new) Solenoid on my trim pump for engine hatch........The one already on the trim pump appears to be the same as a car solenoid like a 90's mustang.
Does it make any difference if the new one should be marine type or just replace what's been there for the last 25 years?.......
https://cimg1.ibsrv.net/gimg/www.off...24e14c59f4.jpg

"MARINE" electronics are spark protected.
In an enclosed bilge with a gasoline engine, an open spark can ruin your day.
Sierra branded marine solenoids are in the $25 range, so there's no reason to dip into your kids' college fund to keep your electrical gear marine-approved.

M

I agree with things that do have open sparks like a distributor and alternator and starters , as those have spark arresting screens built into them. I have pulled my original trim and main solenoids off my boat and opened them up to see what happened and they are no different than a std Ford starter solenoid. The only difference you need to be aware of is some ford solenoids have a ground post on them and some are grounded by their mounting bolts.

I would not consider an automotive replacement. They are not terribly expensive from Mercury. If you are replacing one, replace them both.