under hard drving, the shift from second into third gives me a pretty bad grinding sound. When Im driving slowly, the shift is just as smooth as every other gear, no noise at all. I just really hope this doesnt mean third gear syncro is goin out. Would any one like to add their $.02 and report the bad news?

 

I had the same problem. When I tore the T56 down I found 3rd gear blocker split. At higher speeds the blocker would open under the centrifical force causing high shift effort. Under normal driving it was o.k. but still not perfect. It will only get worse.
If you tear into the T56 buy a D&D kit and a 3/4 fork. The GM parts are not as good. Here's another tip: fill the trans from the shifter mount hole on top instead of the fill hole on the T56 side.