Thread: parts interchangibilty between a 1999 and a 2004 comp g

The internals on the 4T65E are the same I think in both 99 and 04+ and the engines blocks are the same as well. Only difference is in the PCM, torque converter and gear ratio.

Originally Posted by t24moore

The internals on the 4T65E are the same I think in both 99 and 04+ and the engines blocks are the same as well. Only difference is in the PCM, torque converter and gear ratio.

Internals are almost the same but still different.

Everything from 2003 and above has a differnet valve body, newer clutches etc etc, hard parts, and is controlled via the PCM different that than a 97-02.

Flex plates are different as well IIRC.

The motors are the same block, you'd have to swap your brackets and parts over to it to make it bolt right in, then if you kept the GEN V blower, you will have to research on how to make it work on the 97-03 cars. Headers are a must if you went that way, or you could swap your top end over and call it a day.

I cant find anything anywhere supporting your claims of hardened parts, valve body changes, or clutches. GM hasnt changed the 4T65 as far as im aware when it comes to the w-body. Also looking on trannymans site there is no price difference when it comes to these transmissions. Now the Volvo 4t65 has a different valve body but not ours. The flex plate is only different due to the differences in torque converter sizes. But thats more of a NA block versus SC block thing rather than a year specific issue.