Mercruiser 165 6cyl inline. 1977 or 78 engine Starter Solenoid

The Mercruiser 165 in my 1972 Sea Ray died, so I had a Mercruiser 165 from a 1978 boat, installed. The starter Solenoid is not working properly. Sometimes it works and the starter cranks. Sometimes it just clicks. I have checked everything and am down to, it just needs replacing. I ordered a solenoid using the Mercruiser part number for a 77 or 78 engine (I don't have the serial number because the plate is gone) and the part they sent me looks nothing like the solenoid on the engine.
That is a pic of the solenoid on the engine. I have found some on line that look just like this but don't know which one to buy. The engine serial number is in the range 2770032 - 5178958. Unfortunately I could not find these on MarineEngine.com. http://ww2.iboats.com/Mercruiser-St...3282200--session_id.428257971--view_id.373985 Any ideas which is the right one.

I also ordered the other solenoid, the one mounted on the left side under the exhaust manifold and it fit perfectly, looks exactly like the old one, but doesn't work. I installed it, hooked it up and nothing. Double and triple checked the connections. Nothing happens at all when I turn the key. But if I jump the starter the engine cranks and starts, and I reinstalled the old one and the engine cranks. I am assuming it's defective.

Why doesnt the replacement you purchased fit?

Remove current starter, remove current solenoid,
Take pictures of both solenoids side by side and respost.

Suggestion:

Toss that old outdated non-gear reduction starter motor into the recycle bin.
Purchase a new HTGR/PMGR (high torque gear reduction/permanent magnet gear reduction) starter motor.

These spin the armature approx 3 X's faster, will spin your engine over a bit faster and will consume fewer Amps.
Check with our host MarineEngines dot com and see if they can provide the correct one for your application.

some slave solenoids need a dedicated ground to work...without, you wont get any current to the starter...

Sorry I didn't reply sooner, as they say "life is what happens while you're making other plans". Anyway, finally got back to the boat.
The top three are the solenoid on the starter. The next two are the Solenoid I purchased using the Mercruiser part number, obviously not the same. The last one is the slave solenoid. Looks the same, same part number, doesn't work. It's obvious a previous owner of this engine installed a different starter, and I tried to remove the solenoid and there is some connection underneath it to the starter. Its not removeable. I suppose I will have to buy a new starter.

What you are showing is a "slave solenoid"
This is an intermideate solenoid between key switch and starter solenoid.
Also that model, the case needs to be mounted with specific ground to base.

If your earlier post were about the starter solenoid, please clarify!!

this is the starters solenoid, remove the 2 mounting screws, rotate and remove

BtDoctur; Thanks. Do you have a link, or a part number for that. You said rotate. Clockwise? Counterclockwise?

just a plain old gm starter solenoid, and good parts place will have it . The tab at 12:00 in the pic retains it in the starter. 1/4 turn left or right