Good afternoon- I have a 1976 R75/6, mileage unknown but I have owned it 25 years with very few problems. Recently, I decided to fix a few minor and one major issue that I was tired of putting up with.  Bought a rear main seal and the 2 "O"rings for the flywheel and oil pump. And clutch disk. The bike has never been apart until now. My oil pump cover was missing a bolt, another was loose, and the top ones were OK. Just wanted to pass this along.  Personal opinion here-- I like the 1971 4 speed with kicker on it better. The 5 speed is about wore out but was great 20 years ago!