Does anyone know the difference with the 1994 and 1996 4t80e transmission's. The exchange seems to be from 95-99ish. The park/neutral safety switch is somewhat different. I installed a 96 deville in my sls and cant get the car to crank over. Will a 1996 work in a 1994? I guess i should have asked this question before i put it in.

I have a 96 Eldorado transmission in my 95 SLS. They should work just fine, so long as you got the right one. STS/ETC and Eldorado/SLS. You problem is probably an electric connection, or the neutral safty switch. Did you hook the shift cable up right? I had to try 3 times to get mine right.

make sure tis a bse model deville and not a concours tranny

they both have 3.11 gears so i know that isnt the problem. I would imagine it has to be the way i have the neutral switch hooked up. I do not have the shift cable in yet, i just move the selector on the tranmission manually and havent been able to get it to crank yet. Are there any sensors on the motor that will keep the car from turning over if left unhooked?