5.3- 6.0L is a sort of common swap. There are a couple diffrences and you'll have to get the right 1, but a donor truck from a simmilar year can lend an engine wiring harness and ECU for the diffrences. stock ECU can be burned for a 6.0L tune also.. Couple things to remember, 1999-2002 ( IIRC ) engines have throttle cables, 2003+ are drive by wire, and there are 2 versions of the 6.0L that were produced in those years. The Lq4 and Lq9. The 6.0L you need is the Lq4. The Lq9 would work with some effort. It was used in Caddilac only in 2002, but was in the trucks by 2004.. There is 20hp more in the LQ9, probably not worth the extra effort.