What's the difference between model identifiers G, H, R?

[Pogue72]

Hi all,

I'm working on getting a 1976 9.9 model 10R76H up and running.
In researching some things, I've discovered the during this time period the 9.9hp, and 15hp motors where exactly the same, only difference was the carb.

So I was thinking that I may as well look for a 15HP carb.
I keep seeing these 3 letters at the end of the models G, H, or R. I haven't been able to determine what they represent. I was thinking maybe Short vs Long shaft, but what would the 3rd be...

Can anyone help me understand what those letters represent?

Thanks

 

[F_R]

The letters represent any mid-year engineering changes that apply. I'm surprised there aren't more for that year. They had a hard time keeping those things running and kept coming out with kits to fix them.