III TR SSM Lessons learned
 

OK all an old (68-72) mercruiser III will not bolt to a TR gimble bell housing. The six studs do not match.
As the III dosent shift forward/reverse internally so you cant use a SSM lower on a III
And for the same reason the gear sets are different.

If you loose a gear in an old Merc #3, not alpha, bravo, TR, TRS, or SSM you are replacing the whole unit. Which includes inner and outer transom plates. I do not know yet if your transom will need to be reworked with everyone of these options but I suspect the SSM transom plates might use the same template.

By the way I have a template for the III if anyone wants one.

As mentioned in your previous thread, Konrad makes a direct bolt on for the old Merc III (not Speedmaster) It bolts right up to the existing III transom assembly. Feel free to call me for more info. Kurt 715 410 0735

Yep
Planning the bank job as we speak.

I have a TR drive if anybody is looking...apparently they are are hard to find. I bought it by mistake, thought it was a TRS