On my 94 FD 5th gear grinds a little when shifted fast. I have to rev match for a smooth shift. I have a good clutch and new 75/90w non synthetic gear lube. Is this generally fixed by installing the updated 5th gear syncro?

 

Generally yes.

Redline MT90 or MTL is usually a good interim step and often helps compared to non-synthetic trans oil and much better than gear lube.

 

where can you buy redline mt 90? what about mobil 1 75 90 synthetic lube? i know where to buy that.

 

Summit racing carries it. Im lucky enough to have one locally otherwise you may have to order.