third gear grind could indeed be caused by a misadjusted shiftlinkage, but not by the clutch. if the clutch wasnt disengaging all the way it would cause a hard shift in all gears. on our trans 1, 2, 3 all have double synchros, so it probably is you synchro. i have a hard shift into second sometimes. but mine has 208000 miles on it so mine is almost definatly the synchros. try adjusting your cables first and if that doesnt change anything then you know its internal.
it could also be the a bent shift fork. does it ever pop out of third?
