Transmission question....

[Madmunky]

In the months that I have owned my GTP and have been going on to these forums, I have noticed a lot of mention of the 4T65E and 4T65E-HD transmissions. Now, I know these are in newer GP's on the 3.8L, but does my 1995 GTP 3.4L DOHC also have this transmission? Is there a way to tell which it is? To the best of my knowledge its the one from the factory, nothing else has been done to the car.
I figure if anything I probably only have the 4T65E, because I don't have near the power of the newer SC engines. Under what circumstances might my 3.4L DOHC need to be converted to the 4T65E-HD? Turbo maybe? I plan on doing mods in the spring for performance and the transmission is one area that concerns me.

Thanx
Jamie

[StevePT]

You have a 4T60E. This tranny was used from '94 to '99. The 4T65E was introduced in '97 and I believe is still in use today.

One of the visual identifiers for the 4T60E is the vacuum line that runs off the front of the intake manifold down to the front of the tranny and attaches to a "can" sticking out of the tranny. The 4T65E is fully electronic and does not use any vacuum operation.

Oh and for a daily driver car, be glad you have the 4T60E. The 4T65E's, while being a bit stronger than the 60, are plagued by harsh shift conditions normally caused by the electronic PCS solenoid which controls the shift pressure. This is vacuum operated on the 60E

[Madmunky]

So basically because I have the 4T60E and not the 65, theres basically nothing I can do to upgrade my transmission?
Now if I say did something that did require a stronger transmission, like maybe nitrous or a twin turbo set up (for example) Could I put a newer 65E or 65E-HD in place of it?

I want to get as much out of this engine as possible without going through the trouble of doing a complete engine swap to a 3.8L SC engine. (although its starting to sound like the only real option if I want more to do to the car)

Thanx again
Jamie

[BNaylor]

The easiest way to check even without popping the hood is look at the SPID label located in the trunk (under lid), sides of one of the doors, or under the spare tire cover. This label has all of your options, engine code, tranny code and paint codes, etc. A Grand Prix equipped with a 4T60E will have RPO M13 somewheres on the data lines. If equipped with a 4T65E the RPO is M15. The 1997 and up GTP has RPO MN7 and was introduced with a 4T65E-HD (Heavy Duty version) in the 1997 model year. Pontiac switched over completely to the M15 4T65E tranny in 1998 on all Grand Prix models.

Also, the 4T60E will have a smaller electrical umbilical cable versus the 4T65E 20 way plug.

The 1995 Grand Prix GTP has a 4T60E M13 tranny.

BTW - Your GTP does not have the wiring for a 4T65E and the PCM is totally different since it is the device that controls shifting electrically.