Just bought a 98 Sunfire GT with 5 spd manual. The guy selling it said the trans wasn't working. I started the car and shifted through the gears, seemed to shift fine. I let out clutch and car just shuttered a bit and didn't move. I pulled motor and trans out today. When I split the trans from the clutch, I could shift it through the gears and turn it over easily. It made no noise and was smooth in all the gears even reverse. The I thought maybe the problem was really the clutch, no, it looked fine. Last I looked at the hyd. slave cylinder. I looks like it might have jammed on and wouldn't release the clutch.
Finally the question: If the trans turns smoothly and shifts fine, can I assume that the problem was NOT the transmission or is there something else I should look for?
I don't know which trans it is. I see a bar code on it UBM 61UBM 1113A67. The bellhousing has a B-4 on it as well. I would sure hate to put it all together and find that the trans really was broken.

If its the original trans, its Isuzu made. The Getrags came in '00+. Since you said the slave cylinder looked bad, try replacing that along with the throwout bearing (I think they come as a set), then bleed it and see if that fixes it. Hopefully so, otherwise you may need to look into either a clutch, or worst case, another trans. If it IS the trans, it'd be a great time to do the Getrag swap.

I bought the car with the intention of rebuilding the motor, transmission and doing clutch as well. It looks like I might have dodged a bullet with the trans. I'll be giving the car to my 19 year old daughter when I'm done. Just finished doing a Z24 Cavalier with auto for my son. I just pulled engine and left the auto trans alone. With the manual, I had to drop motor and trans down and slide it under the car, little extra fun.

Oh, just a side note. I'm smiling here, everyone here wants a Getrag transmission. On the forum for my car Caddy CTS-V, everyone HATES the Getrag rear differential!