[bobss396]

From my experience, I agree with worn synchros and it could possibly be shifter related if it has too much slop in it. If it had a floor shifter, I'd run a bungee cord from the shift handle to under the seat and that would "fix" it for a long time. Only 1st gear is non-synchro in those boxes. If it grinds going into 1st, make sure the clutch has enough free play in it. It should engage about an inch off the floor.

With the noisy gear box and questionable linkage, swap out the box and look for a newer synchro unit if possible. If you wish to retain the column shift, face the fact that you probably need to pull the column and rebuild it. Chevy used to carry the parts but I'm sure Danchuk or someone else has them. I've done a few on cars and trucks before and you need a good manual in front of you. An alternative is to pick up a Hurst Indy Shifter and convert it to a floor shifter.

Bob