Where to find Serial Number on mercruiser 233hp

I just acquired a "free" boat, we all no there is no such thing. Well anyway, I need to replace the water hoses on the port engine, they are 1976 351 Ford 233HP mercruisers. My marine store needs the serial number to look up parts, where can this number be located?

 

There may be a plate on the back of the engine. They shouldn't need to get serial numbers for a hose, the year and model are enough.

 

Thanks Gonzo for the reply, I would think the year and block information would be enough as well. Just with inboards, unless you are 3 ft tall and weigh 55 lbs, there is not that much room to manuever.

 

The hose from the circulation pump to the thermostat is the same as in a car applicatioin. Some of the others, depending on the manifold style, can have both ends the same diameter of different. If they are the same, you can use any heater hose.

 

Eh?
The hose from the circulation pump on a car goes to the bottom of the radiator?
Only one style of manifold on a 233
There are a few differences between the MIE and MCM (shaft drive or sterndrive) you didnt mention which you have.

 

A small aluminum plate on the bracket that holds the wiring harness connector. After 34 years, you may find just the screw holes.