So i have an 06 silverado im putting a l96 6.0 6l90 all i have is the harness .i changed cabs to a 05 silverado 2500 auto.orginally was a 4.3 with a 5 speed .im stuck on ecu tcm. Driveshaft.and tranny crossmember .google says those have internal tcm.what do i need ?is there a guide im missing somewhere .

 

You need a E38 computer to control the L96 and 6L90e properly and with minimal hiccups.

But if you do that, nothing much of anything else in your 2006 truck is going to function. The E38 uses can-bus to communicate with the BCM and the ABS system. So you won't have ABS anymore and the cluster stuff won't work anymore. And I'm not sure what you'd need to change for the AC system to function with the newer computer either.