not to resurrect an older thread, but i feel i need some advice.

some of you have seen and replied in my other thread about my A833 grinding when i make the 1-2 shift under partial or hard throttle, but not under very light acceleration. I have taken the whole transmission apart and inspected every peice, and everything is working and worn as it should be with no visible issues at all. I changed the fluid in the transmission to AC delco synchromesh, and now im wondering my problem is the fluid im using?

Im thinking of trying ATF since i see quite a few people recommend it, and since its also dirt cheap and there is no non GL5 gear oil on any shelf here. Im wondering though what kind of ATF should I be trying? Dextron? Mercon? straight ATF? does it matter if its Dextron 3 or 4? Just looking for some input here since id like to refill the trans with ATF and see what happens