John, I've got DTT's TC + VB. I also use Amsoil transmission fluid. The truck has 4:10 gears and I watch the transmission fluid temps. To be honest, until these upgrades, I'd wished I ordered a 6 speed, but now I'm very happy with the performance,I pull two different trailers also. I also know being a drag racer,that if you continuosly beat on something that eventually somethings going to break,I accept this. If you check,the bombed manuals are having there problems also. So far , I'm so good,for how long, I don't know.