Merc pre alpha trim pump thread sizes help

Jakecsam

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Joined
Apr 15, 2026
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4
Okay so I have a 1980 Chris craft Catalina 25 with a Mercruiser 260 & a pre alpha drive. It has the….
66397A1 76812A4 Reverse Lock Valve Shift and the trim pump that is currently installed on the boat is a MerCruiser 79271A4. I have the two braided metal hoses ran from the outside manifold nicely, but someone has been in here before & seems to have played around. So as it sits right now I have the 2 hoses coming from inside, the 4 connected at the rams all good, a pump that works but no fittings on the pump. I was going to bypass the reverse lockout so I put some plugs into the ports on that and wanted to straight shoot the two hoses from transom right to pump, problem is there’s no fittings on the pump & I’m assuming they’re two different thread sizes. I work at a marine shop so I have tons of stuff laying around I can make work so just wanting some advice on what would be my best option ? I can still run the reverse lockout, would just like some direction possibly ? Thanks in advance.

Also I do have a set of the newer style black & grey hoses that fit into a newer style manifold on the t plate (7-16 inverted flare as opposed to the older braided ones I have that I think are 3/8)
Also have a few other different style trim pumps laying around ( I added photos to this post ) and maybe one of those could be plug and play ? But also hoping I can just get the old existing one plumped properly, seems like a spring and bearing ball might be missing any help is appreciated
 

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