I'm going to be pulling the engine soon in my '90 z24, and my th125 is starting to slip a little, and I found one from a '91 RS, and I was wondering if there were any differences in the VSS, gearing, or TCC?

There should be a colored data plate on the transmission with a three letter code on it, get me the codes and I can look up the gearing and torque converter stall speed.

Ok, i'll look when I can, my car currently isn't at my house right now. And where exactly is this plate?

On top of the tranny, on the drivers side.

Ok, hopefully i'll get a chance to look tomorrow, and i'll call the guy with the other trans and see if he can't give me a number too. I'm supposed to go look at it on thursday, so having all my information in order would be really nice. Thanks for the help, and even though i'll say it again later, thanks in advance for checking the numbers.

LH C

J 258C OLKC

And this is the number the guy gave me for the other transmission - 91 AYC 13127

I'm not showing a listing for LHC.

The listings I have for '90 3.1L V6s and any code close are LAC & LJC w/ Final Drive (FD) of 2.84 and sprockets 37-33 this comes to an effective drive of 3.18. ( [37/33] = 1.121212, 1.121212 X 2.84 = 3.1842423) If you haven't already, read this thread, for an explanation of the stall converter codes and sprockets.

There is also LKC & LLC w/ FD of 2.84 and sprockets 35-35 for an effective ratio of 2.84.

Finally there is LUC w/ an FD of 2.84 and sprockets 33-37, for an effective ratio of 2.53.

All those list the same Torque Converter code of FJAB w/ a stall of 2060 rpm.

The '91's AYC is from a 2.2L TBI with an FD of 2.84, sprockets 35-35 and TC code FK1B w/ a stall of 2760 rpm. This TC will help if your after more performance, allowing you to stall at a higher rpm and higher launch rpm. The gearing is middle of the road for this motor.

IIRC both model years use the same mechanical speedometer drive, so it should hook up the same. The pick-up for the speedometer gears is on the FD sun gear case and will dive at the correct speed irregardless of gearing or sprockets. The TCC solenoid plug could be the same. There are four listed (no year or model designation) 2 prong, 3 prong, 4 prong round and 4 prong square.

This should answers most of you questions, if not I'll see what I can do.

Thank you VERY much for all the information. I am more drivability oriented versus performance oriented, so i'm going to plan on switching the torque converter from my trans to the new one to keep the same stall speed. I'm also going to go double check the letter code on my trans to see if I didn't read it wrong and I can find out exactly what gearing it is.

I just went and checked, it's an LK C, sorry for the misinformation