freshly rebuilt tranny...grinding!!

Ok so I didn’t wanna post this cuz i’m usually able to answer my questions thru searching but I can’t put an exact answer to this one. I recently had my ys1 tranny rebuilt maybe 3 months ago. It was filled with Honda mtf. Got a few bottles of the GM synchromesh fm from a friend and decided to swap out the Honda mtf for the gmsmfm while I was already changing my oil n filter. So a few days after the fluid change i’m getting grinds going into third and fourth over 3k. I’m already planning on switching back to the Honda mtf this weekend. I got under my car yesterday and noticed my shift linkage seems to have alot of play like at the u joint part. Not sure what else to check or what it could be. I tried adjusting the clutch in n out with little to no improvement. also checked the synchros by turning the car on in neutral with the clutch out and nearing the shifter towards each gear. As I get close to each gear the RPMs do drop instead of just grinding.not sure if that’s a good or reliable test but I read it on a couple forums…anyways looking for any inputs or tips and or adjustments that anybody has. Thanks g2

I personally prefer running the Honda fluid others swear by synchromesh. both are known to help stop grinds and chips from worn synchros, so one would have to wonder WTF is exactly happening in your case.

I would definitely get the linkage taken care of also check the bushings.

Yeah its kinda weird how it started a few days after putting the gmsmfm in tho?. its supposed to fix grinds, not that I really had any, but in my case its causing grinds??idk also noticed my rear mount bushing looks a little worn but idk if that would cause the third and fourth grind… I do have a brand new innovative rear mount just gotta find time to swap em out, cuz I kno its gonna be a pain.lol also no grinds or trouble downshifting.only on the upshift…

hopefully whoever rebuilt it looked at the hubs and the shift forks