Everytime I shift sometimes on the first gear, but more often on third gear that I hear the grinding noises when I accelerate. What's causing this issue? and what can I do to resolve it. Does it have anything to do with the synchro? I just changed the tranny fluid few months ago thinking it would help, can putting a better fluid like synchromesh tranny fluid make a difference? Thanks

 

Might be synchros, might be gear sleeves, might be gear sets, might be your actuator arms. You'll know when you pull the transmission apart to find out.

 

It's an old car what do you expect ? my bet is worn gear synchronizer(s) sounds like typical symptoms you've described.