I bought a 2000 cavalier, 4 cylinder with 3 speed auto transmission. Trans tries to pull forward in park and no reverse. I have another transmission that was from a 2001 cavalier, 4 speed overdrive transmission that is good. I am wondering what is involved in switching them. I have noticed the electrical plug on front of trans but the cooling lines is different. The 3 speed only has a couple wires in a square plug and 4 speed has about 20 wires. The 3 speed actually has a trans dipstick which I have not seen before. All I have seen just have a red or black fill cap. Any help would be greatly appreciated

 

the 4 speed has no dipstick. the fluid level is checked at a fill plug on the transaxle case with the engine running. you would also need the pcm from the 4speed transmission as that is what controls the transmission electronics.
there may be a write up on jbody.org

 

Yeah OP has the 3T40 transmission going to a 4T40e. I suppose it can be done.Plus the 4T40 has overdrive too.

 

Which motor do you have in you Cavalier?

 

2.2 engine

 

Yeah that will mate up with the 4T40 bell-housing. The 2.0 liter wont, but its been awhile since that was around. Its the electronics that will take some work.

 

Will I have to change the whole harness?

 

I believe so, but truth to tell, I not not positive about that. I know that you will have to install the ECM from the 4T40 vehicle in however.

Whats your gas mileage at 65 MPH now? My 2005 Cavalier would do 33-34 MPG at 65 MPH. The 4T40 should increase your gas mileage too