Hi, can anybody tell me which parts I need for fitting a 12 rivet output shaft in my old engine ('84)? Thanks!

ReneZ, I cannot comment on your quiry, BUT....I would like to know what the symptoms were that caused you to tear into the motor to up-grade the output shaft?

Was it noisy on slight deceleration, a kind of grrrraaahh rattling noise..?
Curious.
Thanks,
Rick

Particularly noise, specially on braking on the engine with a cold engine. It might not be the rivets, but I would feel a lot better going on longer trips with my son as pillon if the shaft was exchanged.

Mine (1989 rt) makes the exact same noise on deceleration when not up to operating temperature. I've always suspected it to be the spring in the gear backlash eliminator as they are known for sometimes wearing in the locating hole in the gear. I don't think it is the rivets loose as my previous (1988) engine had loose rivets and it made the typical knocking sound at idle, the '89 engine doesn't do that.
I think Bert has written about this in his resto article some years back.

I cannot find any information about the swap, but I think that I read somewhere that the bearings are different (something to do with a grooved bearing and the location of the retaining clip on the crankcase). You may need an extra spacer. (maybe not).
Best is to go to see a dealer and have a quote for all the parts needed.