The syncromesh didn't work for me. I had the 3rd gear grind too, and tried the GM syncromesh as an option suggested by quite a few people. I'd heard really good stuff about it, and I still believe most of it, but it definitely didn't work for my car. I'm guessing the syncro wasn't extremely wasted because I didn't have any problems in any other gear, including 5th.

My fix was to replace the tranny. I searched around quite a bit, looking at used, rebuilt, junk yard, etc. I ended up finding a Gearspeed Type I tranny that some kid ordered and bailed on, so Gearspeed was selling it on Ebay for $550 instead of $1300.

While I was doing the tranny swap, I put an ACT clutch and flywheel in it.

If you’re having syncro problems, my recommendation is to replace the transmission. It’ll cost you a little bit more, but will save you the time of actually rebuilding the transmission. Also, if you use re-manufactured stuff, its pretty much just like new, and you won’t have to worry about syncros going bad anytime soon like you might have to worry about with a used tranny.

There’s my 2 cents.