1965 Mercury 500 parts question

[matma]

Hi, I've got a 1965 Mercury 500 which I'm rebuilding. Previous owner didn't put the splined washer on it correctly so part of the bearing carrier and prop was grinded down and am in the process of replacing it.
Now I've found a not running 1969 Mercury 500 for about 100$ and was wondering if the lower unit is the same on these.
I've been searching around and they do seem to have different partnumbers although they look very similar.
Anybody have any experience with this as it would be an inexpensive way to replace the lower unit and prop and have other spare parts for mine.

 

[jimmbo]

While there might be some internal differences, a complete unit should bolt on. Unless there was a change in driveshaft splines or preload pin

 

[Chinewalker]

Make sure they're both the same shaft length. Both came in long and short shaft flavors.

 

[matma]

Thanks for the replies. I've since bought it and it sits in my garage, they're both short shafts. It's a handstart but has the toothed flywheel, which is good since my '65 already has the starter motor but was missing the correct flywheel. I've not yet tried to swap the lower unit as I'm first cleaning it up a bit.
It's missing the stator and rectifier, which I will probably add in the future to be able to charge my battery.

At least now I can measure it up to see how bad my '65 lower unit is in terms of material that's been grinded away although it seems to be mainly the prop and bearing carrier that suffered the most damage.

Aside from the electrical changes (the '68 has a switchbox and ignitioncoil) the rest seems similar and for 90$ I've got plenty of spare parts to use.

 

[ssdale]

I think the shift mechanism is different int he 1969. The splined shift shaft is the same, but you may have to make a spacer to get the height of the 1969 LU transmission cog to match the 1965. When you get them apart, you will see what I am talking about. I believe ou can make it work. Good luck,
Dale