jimnance, Why would you want your truck to shift into 4th at 2500RPm"s? I think your transmission shop put the 12v valve spring in the valve body,instead of the 24. Peak power is at 2700,shifting at 2500 isnt good,espeicailly with a big trailer. 2800-3100 is where you want the shifts to be on the 24 valve. I like 2900 on my truck,it seems to be quickest at that shift speed. I put a trans go kit in my 96 a few years back,I had a #6 TST plate,and The lockup was starting to slip(I had a lockup switch). I had zero porblems with mine,it was about a 6 hr install for me,but everything worked perfect,the shifts were nice,and solid. I didnt have to go back in ,it went perfect the first time.