Q: What are the major differences or advantages between the greasable bearing and the non-greasable one, I have 1961 S80, which one is preffered?
A: Really there is no difference in the bearing besides a notch in the greaseable one to line up with the grease hole in the collar to be greased. I'd just get the cheaper option.
Q: Currently have a non greasable throw out bearing will the greasable throw out bearing working it’s place?
A: Yes, it will work.