4t65e swap into Ecotec ... what TCM to use?

I am putting a 4t65e from a 2000 Grand Prix behind a 2006 2.4 Ecotec. The Ecotec uses an E67 ECM and T42 TCM. I'm not sure what the Grand Prix uses yet. I know its not a T42 but I also know that T42's were used with 4t65e's in their later years.

This swap is happening even if I have to buy an aftermarket controller or just run the transmission off of toggle switches without a TCM at all. BUT if I were to use a TCM would it be better to use the Ecotec T42 to control the 4t65e and copy all the tables over from a 4t65e application that I know used the T42? Or is it better to use whatever the 4t65e uses and try to get it to play nice with the Ecotec E67 ECM somehow?

This is going in a dedicated off-road only vehicle and my ultimate goal is to achieve full manual control of the transmission.

Think I answered my own question. The Grand prix uses a pcm and not a tcm. So I will probably need to use my current t42 and make it play nice with the 4t65e.

Anyone got any advice?

Whatever you swap in pay attention to the drive sprocket ratio from each tune. Did you also consider an actual manual transmission from a '90s Grand Prix or Grand Am?

I'm going to be changing sprocket ratios anyway so I will pay attention to that. Thanks.

I had considered a 4t60e, still am as well. But the primary reason for the swap is the 39-spline passenger side output shaft / HD version of the 4t65e and I wasn't sure if that could be swapped into the 4t60e. The 4t65HD also has chromoly driver side output shafts available on the market which may be of use to me in the future and again, not sure if they can be used in a 4t60e. Finally, the 4t65 enjoys a lot of aftermarket support and the 4t60 enjoys none.

I'm still experimenting. There are so few people who know anything about these transmissions I find that I am just having to figure it all out on my own.

I spoke to Dave at Triple Edge Performance about my 4t65e swap and achieving full manual control. He agreed that my 2 options were using switches without the TCM and just living with full line pressure all the time or getting the 2001 trans to play nice with my 2006 TCM. Fortunately, he said that my Cobalt TCM should control my Grand Prix trans just fine simply by copying the tables over from an application that did use the T42 TCM with the 4t65e. He said the pressure control valves were a little different but that can be tuned, and even if not, isn't that big of a deal. So it appears that is the route I will be taking!