Welcome to the forums!
The crankcase and trans should use the same oil. There should be a plug on the bottom of the engine. I'll see if I can find an exact location for you in a picture. The oil you should use needs to be certified for a wet clutch. Best bet would be Honda GN4 10-40 oil. Amsoil also makes a great wet clutch oil and we have a rep here on the site if you would like that.
I have one. It's a classic and I'll never sell it.I agree with Fourtrax. The 1984 Fourtrax 200 was the first ATV manufactured. They had 10 gears(5 in high and 5 in low). They have about the same body style as the Fourtrax 250. The Fourtrax 200 was the first 4-wheeler I ever owned. You don't see many of them anymore.