I just picked up my first Cummins. 1996 Cummins 12 Valve with 233k Miles. Mechanically sound Body is hell. But i bought a southern 96 1500 for the body im about 7grand into this project, Well i was driving the cummins home from work today, Stopped at a light took off fine got to about 45-50Mph It didnt feel like the trans slipped, Felt more like it just changed gears my rpms went a high, More so it felt like i hit the OD button the dash then it went back to normal and my rpms went back down, It did this twice in a row then was fine for the rest of the 25min drive home. I even messed with it driving, Shifting it in and out slow speed high speed, I got on it hard. I know these 12v's dont have much Nut off the line. i just dont want to put all this work into changing the bodys over and have my tranny go

 

most likley it was just cold fluid ... mine does this occasionally ..... once warm its all good