If you drive is an '81 then it should be a hydro-mechanical shift, like mine and Boomyal's. If that is the case than you need 80w90 marine gear oil for the intermediate, upper and lower gear housings. You can get it at Walmart in the boating aisle. I think Boom is thinking that you have an electric shift drive which does use the Type-C gear oil in the lower.
Yeah! I don't know where I got the idea that it was an electric shift. Must have been mixing it up with another post. I see, now, that it is an '81. That should make it a hydro-mechanical that uses 80w-90 in all three cavities.
