Swapped in a 6.0 4l80e combo in my 97 k3500. Truck runs fine, but for some reason in the scanner, not on the dash, When in park it reads d4 and sometimes in drive it will flash park. The dash goes through all gears correctly and goes in to all gears correctly. There's no rhyme or reason I can think of why it would do this.
Driving down the road it shifts through all gears tc locks up, in hp scanner I can command all gears force the tc to lock up.
Anyone have any ideas on what could possibly be the problem ?