im looking at diesel trucks...dont ask why i have always liked them. Anyway im looking at dodge and chevy, i dont want anything newer then a 04. i want to put a big fuel injection system with a turbo.
Not sure what you mean by "big fuel injection system" Diesel are all fuel injected, or they wouldn't be diesels. I wouldn't monkey with the injectors on any modern diesel if I was you, they can be under extreme pressure, like several thousand psi, the newest ones are well over 20,000 psi. I wouldn't monkey with any of the aftermarket ECU chips/reflash like Banks etc either. I've seen to many engines ruined by people hot rodding them by re-chipping. I know for a fact that the Banks chip will melt the heads on the 6.0L Powerstrokes if you're not very careful.
I dont know much about diesel engines, but i hear cummin's engines are the best out there. Also another question, if i go with a turbo, should i go with a twin turbo or a single?
Any truck you buy that is mid '90s or newer is guaranteed to be a turbo, single. There are aftermarket ball-bearing turbos that sound cooler then the stock ones, but I don't think they make a huge performance difference. Both the Cummins in the dodge, and the Duramax (Isuzu) in the Chevy are great engines, as is the Powerstroke (International) in Fords. They are all good, just different.
FWIW I've driven all 3 quite a lot, my father owns a 2004 Dodge Cummins, my brother a 2002 Ford Powerstroke (International) which he has now replaced with a Kenworth sleeper, and my work truck once was a 2006 Chevy Duramax (Isuzu)
All have there strong points, Cummins is a inline 6, while the powerstroke and duramax are V8s. The V8s will cruise at higher speeds towing heavy loads slightly better, but the Cummins tows hills and stuff just as well and gets slightly better fuel economy. IMO Chevy has the best automatic tranny for towing/hauling with the Alison, but they all work.
If I could build my perfect truck it would be the Duramax/Alison combo from a Chevy in a Ford body/interior.
PS. If you end up looking at Powerstrokes, I'd recommend the 7.3L over the newer 6.0L.