i have a 2003 2500hd with 105k miles. at 95k miles i installed a 7-9in cognito lift with 37in toyos. for about 15k miles ive had a quadzilla set to 135hp. when i get on it from a stop it takes off fine until it gets into third gear then i seems to just rev up and not really pull but if i let off alittle it seems to pull harder. is my tranny slipping? it only does this in third gear and it never goes into limp mode. whats wrong? thanks

i have a 2003 2500hd with 105k miles. at 95k miles i installed a 7-9in cognito lift with 37in toyos. for about 15k miles ive had a quadzilla set to 135hp. when i get on it from a stop it takes off fine until it gets into third gear then i seems to just rev up and not really pull but if i let off alittle it seems to pull harder. is my tranny slipping? it only does this in third gear and it never goes into limp mode. whats wrong? thanks


big tires , stock trans and 135hp tune......... I would say your on borrowed time , set it to stock power level any maybe you can get a few months out of it. stock trans can only deal with about 70 ~ 80 hp more then stock , big tires just lets you load the motor down harder.

Have you changed the fuel filter since you owned the truck? Start there, then change the tranny spin-on at a minimum. Mark is right though, you are on borrowed time on the tranny. It doesn't sound like you are limping it yet, but once you do, it gets easier after that.