Hello, new here obviously. Just picked up a new to me 03 Duramax 4 door short bed. It's all stock with around 70k on the odometer. The transmission feels like it is slipping already in 4th and 5th gear. I bought it used for a great price so I don't mind putting a little money into it. Should i take it too the dealer for the 30 day warranty? what should i tell them to get them to buy a new trans?

I would take it back to that dealer for your warranty. I bought a honda civic last june and they gave me a 30 day warranty also. The place was a little hole in the wall, and the guy stood by the warranty and fixed the a/c after it stopped working. It wasn't an easy repair either, they had to take the whole dash apart. I would take it in asap and make them rebuild the trans, and give you a reciept from wherever they took it to. Just my .02

Yeah what he said. Sounds like it had some heat (high hp tune) on it before they dumped it.

Oh and welcome to the Place!

i took it in today, of course they say there are no issues..:rolleyes:
I got the feeling they didn't want to have to put the money into it because I priced the trans and it's spendy