sweeeettttt i meant to type 8l90. i was waiting patiently for marks 4wd adapter to make a 8l90 adapter as i have a 2017 lt1 with 8l90 waiting to be installedIt's an 8l90 transmission and the Black Box is the adapter. You order it made for the transmission and transfer case you intend to use. If you scroll up and look at the picture of the transmission it's the back tube in between the transmission and the stock Toyota transfer case.