my '98 taco still grinds when entering 4th gear, whether from 3rd or 5th. i replaced both the shifter socket and the seat with heavy duty marlin crawler urethane to no avail, except for a rock-solid, brand new shifter feel, no "slop" whatsoever. Even at low speed, if you just BARELY nudge the stick to 4th, it feels like it straight up bypasses the syncros and grinds like crazy. AND, it seems to do it more consistently after the truck has been ran for 15-20 minutes and the temps are brought up.

it has been suggested, several times now, that my syncros are bad into 4th gear. ive been looking for a few straight days now, and i cant find a single vendor with a syncro set for w59 trannys. if actually finding them, and then installing them is a huge hassle, is it in my interest to just look into buying a used/rebuilt 5spd and bolting it in? help, please!

finger

 

AFAIK the synchros are only available from the dealer.

Unless you wanted to rebuild it yourself, you might try looking for a used tranny to swap with.
.....then just swap over your aftermarket parts.