Gen V/ 8l90 tap shift question

[Lonniec]

I am in the middle of a LT swap on my 67 Nova and am trying to figure out to make the tap shift work?
What I am trying to achieve is to be able to utilize the stock shifter from a 18 Camaro that has the manual slap shift function and the indicator display right beside it. I am running into a couple issues though, a) I can?t seem to find the correct harness to plug into the shifter and the indicator and B) trying to figure out how to tie the system all together!

From what I understand the shifter harness (that I can?t find a pt# for) runs to the bcm with a gmlan wire the the bcm send a second gmlan wire to the tcm to signal the tap up or tap down function.

So my question is this, can someone with experience tell me if what I said earlier is correct and what other headaches will I run into by wiring a bcm into the car? Will the bcm also need a communication with the ecm? Will the bcm work right if all of the other circuits dead? And last but not least how hard will it be to flash a bcm to communicate with all my other systems?


i hope this belongs in this forum?. I feel it?s definitely on the more technical side lol

[crankz1]

Mitch at https://www.swaptimeusa.com/ might be able to give some guidance

[Lonniec]

Mitch at https://www.swaptimeusa.com/ might be able to give some guidance

Mitch is who built my engine harness. I?ve had a conversation with him about it, at the time I didn?t have my shifter purchased yet? he sent me a pin out on the connector to the shifter as well.

[crankz1]

Nice. I am not smart enough to know what all would need to be done, but his brain is one I would want to pick if in need.
He just put out a video on a Wagoneer with an lt4. It is a truck OS, but he has got the tap shift working on it.
Obviously there is a way...