This does not fit a GT80. The side that mounts to the handle bars is a perfect fit but the end that goes to the splitter for the carb/oil pump is too big.
I made mine work but do not buy this is you are not willing to have to fiddle to make it fit.
If you still have your old cable then it can work, you just need to reuse the old plunger piece.
you should know i orderd this for my 1975 gt80 and it is the wrong one this cable#36726311-01-00 is for yamaha 80's 1974 and older newer then that takes #462-26311-00-00 would you happen to have this cable that i need