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Ok sounds good let me know what you find on 35hp? 

I was referring to my 1957 Evinrude Big Twin.

All good John you mentioned one of your powerheads had same leak.

I have a 1956 Evinrude 30 HP Lark but I don't have any plans to remove the power head. 

Boatboy 

agree yours is most likely 1st addition specially if your 1955 part number matches it, I’m very interested to see if that exhaust loading plate has two tubes on your motor. When powerhead comes off let me know, maybe we can determine the difference.. your part number I’m not able to find still.
in the end I guess I should make a blank plate for mine at the very least. Which is what matches number I have.
be interested to see if there’s a hole joining water exhaust and motor exhaust below this plate in your leg if you have tubes on plate..
appreciate you looking deeper for me. 

My parts list doesn't have anything on it where yours says second edition.. I guess that means mine is a first edition. 

I also have a 1955 parts manual for the 25 HP Big Twin and it is a second edition. The part number is 376330 in the 1955 manual, same as in my 1956 parts manual.

Maybe they superseded 376330 because tubes were breaking off? Just a guess

wonder what 1955 25hp had?

Mine are second addition 

That’s bizarre I have two in digital I’ll compare to see if there’s difference.. mine were sent by a great lady down your guys way I don’t have hard copy..
thank you but confused why on earth they’d be different..

when I put your number in marine engine .com it’s a N/A number 

Curtis, I just scanned my 1956 Evinrude parts list and the part number for the exhaust loading tube assembly is different than the number in your parts manual.