2012 6L80e Backdate With Older T43 OK?

Hi all. Have done some deep diving, and mostly come up with the same story, but there was one exception, so now my confidence is dented.

I have a good buy lined up on a 2012 6L80e 4x4 trans, but I want to adapt it into my 2009 Colorado (factory V8/E67). I understand there is a communication protocol change GM made in 2010/11 with the T43, so there is strong advice to simply match the year, therefore I should be targeting a 2009 6L80e and be done with it. I can get the 2012 6L80e for $650, and a used 2009 T43 for $100. A 2009 6L80e is otherwise $1000 and up.

I did find one article saying there was a corresponding change made to the valve body at the same time, so now I am confused if you can simply put a 2009 T43 into a 2012 6L80e, or not. I think so, but now not certain.

I do have full access to GM MDI tools and subscription, if I am able to back-date the included 2012 T43 to 2009 operating system, but I think even with the proper GM tool this is unable to be done? Or, is that only the case with aftermarket re-flash programs such a EFI-L and HPT?

End question becomes, will a 2009 T43 fit and work in a 2012 6L80e?

Thank you in advance. If I missed a similar article, apology.

Hmmm I'm not sure honestly, I think if you try to flash an 09 OS into the 2012 T43 it will brick it. I haven't done enough switching of OS' to know for sure.

This is something a J2534 device will need to do, EFILive and HPT will likely not be the correct way (especially since you'll want to pick a certain make/model). I havent had an issue with SPS not allowing flashes, it does not have the same checks that EFILive and HPT do (not necessarily a good thing).

Even if using the proper GM MDI and subscription, it may not accept it I think? My reasoning here is that I believe there are 2 different T43 part numbers, one for 2007-2009, and one for 2010 and later.

Another possibility, would be to uprate my 2009 E67 to a 2012 operating system, and not have to change anything in the 6L80e? Or, would my 2009 Colorado not like that?

Any other input is appreciated.

You'd have to find out if GM made any changes during the production cycle, but I doubt they did. You'd have to find a 2012 E67 and flash that, probable be easier than trying to swap the TCMs out.

For the 2010+ TCM's GM made some specific changes that meant you could not flash in earlier programs, even with TIS it just doesn't work. It won't brick it but the flash will never be able to complete to the point where the TCM will be fully functional.