I'm not sure if you have ever heard of this, but it is called GM Syncromesh. You can go to any GM dealer and pick this up. It is a little expensive, about $10 a bottle, but is well worth the investment. I put two bottles of this and two bottles of 80w-90 synthetic gear oil in my transmission after my clutch/flywheel install. Gear shifts are much smoother and putting the car in first gear isn't as tight as it once was.
Here check this link out
http://www.i-club.com/forums/showthr...ght=syncromesh