Originally Posted by bajabro

I have the 11 on mine and after a 5 to 6 minute run i pull my truck off and its usually between 150-160 degrees. I need to get the 12 tooth pinion to try it out and see the difference. Dave was saying that the guys running the 4.5 motors are mostly running the 12 tooth pinion. With the 5.5 i would think the 13 would be good.