Transmission compatability

Hello all, I have a 2000 Lesabre Limited that now has a toasted transmission. After pulling the pan and seeing all the pieces of gears and needle bearings, I realized that a new transmission is in order. My problem is that, in the year 2000, GM put 4 different transmissions in the Lesabre. The transmission in mine has the code 610PAB on the tag. Most of the cross referencing I have done refers to this transmission number as 0PAB. I have found an '03 donor car with 92k miles on it that I can get the engine and tranny both out of for $850. Trouble is, I'm not sure if the '03 tranny will match my '00 computer. The code on the donor transmission is 3PAB, and as far as I can tell the gear ratios are the same. Can anyone offer any insight on this? I need to move quickly on the donor car as there are several other potential buyers waiting to snap it up if I don't.

Look at the rpo tag in the trunk and find the "m" code this id's the trans and final drive gearing, then check the donor car.

There are two codes on the tag that start with M, they are MN3 and MX0. Are these the codes you are referring to?

Check this link to match up your final drive ratio/code. http://www.c2e.info/rpocodes/gmrpocodesGthroughM.html

Thanks, I checked the donor car and both M codes match mine exactly. Also managed to get the engine, transmission, and both drivers side window regulators for $775. Looks like I have lots of work ahead of me!

Okay, I just got the new transmission in the car and on test drive, I am only getting 1st and 2nd gears and reverse. Did I forget to do something or is there a major problem? I test drove the new transmission before purchasing and it shifted fine through all gears at time of sale. This is somewhat frustrating after working through the night...any ideas?

Okay, I just got the new transmission in the car and on test drive, I am only getting 1st and 2nd gears and reverse. Did I forget to do something or is there a major problem? I test drove the new transmission before purchasing and it shifted fine through all gears at time of sale. This is somewhat frustrating after working through the night...any ideas?

Although the trannys may be the same, perhaps the internal wiring harnesses are not the same and thus the signals for shifting into third and overdrive are not being passed on. Unfortunately the only fix would be to either:

1) Remove tranny and swap internal wiring harness from old tranny to new (unless you could remove side cover while in vehicle,) or

2) Find out the exact pin out of each tranny and swap the wires on your external harness to match the old one (cutting and splicing the car's harness to match the correct pin positions on the internal wiring of an 03 tranny.) The best source I know of for this info is a tranny book from ATSG. The book will have the pin outs for each different tranny that the 4t65e had.

It may be that your wiring and the 03's wiring are the exact same and your problem in something else in which case you'd need the tranny scanned to find out what is happening.