Mercury Lower Unit

[strosk]

Hey Y'all...

I bought a lower unit and it didn't fit. Now I'm stuck with it. I'm trying to find out what models it will fit so I can sell it. All I know is the casting number 1643-6458. Also, it was advertised as a 1972 Mercury 650 LU, but I'm not sure about the number of cylinders or accuracy of the ad.

Any help is appreciated!!

 

[Moody Blue]

Re: Mercury Lower Unit

What is the gear ratio?

What is the diameter of the casing at the prop shaft end?

What is the driveshaft length?

 

[strosk]

Re: Mercury Lower Unit

I don't know the gear ratio. Is there any way for me to find that information on LU?

The casing is about 3 1/2 or so... just about identical to my 1987 Johnson 40hp, which is considered a small gearcase.

The driveshaft measures 21 /1/2 from the top of the water pump.