Well I have about had it with my 98 zx2 transmission. Done replaced it twice and now Im about to have to again. I can’t downshift to third unless I push clutch in halfway and rev up a little for it to slide into gear but has no prob going from 2nd to 3rd. I thought maybe my clutch but had to many ppl say our transmission are shitty so can anyone please tell me were I can buy one online built for performance and is a resonalble price.

I am not aware of any places to buy good built trans. I have heard of people cryo treating the shift forks and other internals to make them stronger, our stock differential is weak, but this dosent sound like your problem. But to fix this issue with the diff. most people have been going with a Mfactory LSD, in the past I have seen people using phantom grips. 98 trans are the more sought afer because the have a longer gearing. Those are just a couple facts for you, I dont really have a answer for you problem though, sorry.

Have you tried using GM synchromesh fluid in it? Were the blocker rings replaced during overhaul? Or, was this just another used unit from a donor vehicle?

Driving style may have something to do with it, it sounds like your synchros are going bad. That or shift forks. If the problem is recurrent thru several trannies though its that probably the synchros aren’t getting enough time to do their thing. If it’s a one tranny deal I’d guess possibly a shift fork

well it grinds everytime i put it in 3rd and its done that in both transmissiion so how do I change the synchros.

First, check the cables very carefully. If the eye bushings are worn or the levers are loose on their shafts, or the shifter bushings are worn you will have shift problems. The key here is the problem occurs on the 3rd gear transition which involves moving the detente lever during the shift lever movement. Check that shift control system from stem to stern with a very careful eye. I have cleared up a lot of shift complaints by repairing the shift controls.

yep - do clutch adjustment and shifter bushings, and drain/refill your trans with a 3/1 mix of atf and hyper lube.