Truck just revs after driving fine, code P0300

Okay, thanks. Now I'm having a hard time see what type of transmission I need for it. It has 2hi awd 4hi and 4lo. Could you possibly tell me what kind I need so I can tell the guy I'm not around the truck at the moment or I would check.

I forgot about that. Sorry, the past couple days have been pretty hectic for me. I will check it out thanks again.

Will do, thanks.

Ok I got 1 more question ive looked up from a few different forums about the transmission in my 2004 trailblazer and the 2005 trailblazer and from what I read they are the same transmission I just want to double check and ask your opinion on it its just incase the transmission the guy has (who I bought the truck from has the wrong one) I juat want to make sure if they r compatible with each other even though the 05 is awd and the 04 is 2wd