Please help me identify model year of 25HP Johnson

I have a 25HP Johnson outboard on a boat my dad gave to me. He bought the motor used and it has no serial plate.

It is a long shaft motor with electric start and remote controls. Attached is a picture.
The carb says "HQ 432700"; soft plug on the head says "G303961B"; right side transom bracket is stamped "19101" and "188"

I need to replace the water pump and am also having trouble getting the lower unit off. Bolts and nut are off, shift linkage is disconnected, and the loose threaded part and plastic bushing are on the lower rod.

Thanks for any help

The wee plastic keeper on the bottom of the upper shift rod is split and it must be removed.---------Motor looks to be 92 / 93 year.

Thanks racerone.

On the shift coupling, it appears that the brass portion on the upper shaft is solid/fixed and that the loose coupling with black bushing inside is on the lower shaft. It also appears that the hole above this coupling is large enough for the lower unit casting to clear it as it drops.

Anyway, I'm thinking that what is stuck is the stud at the front. I can see light thru the gap everywhere else toward the back. Been trying penetrating oil, vibration, and gentle impacts on the stud as well as the front of the lower unit casting.

Sorry , the upper shift rod also has a plastic keeper that must be removed !!!!!!!!----Perhaps the paint prevents the nut from going up to see thuis simple fact.------And I own much more that one of these motors.

OK I will see if I can get the upper coupling apart.

I need to get the front end of the lower unit free before this will matter. Something around the stud seems frozen; otherwise the lower unit is separating.

Do you happen to know the water pump kit PN for this motor?

Thanks

Well, you can look up the part # for yourself right on this page.-----Engine diagrams.-------You will also see how the upper shift rod is made !