If its a NBS truck its got the 5.3. I think all you'd have to swap out would be the engine wiring harness and ECM, but I'm not entirely sure.
On the other hand, I really don't think that its worth swapping, the diferences in power between the 2 are minimal. But, if you can do it for cheap, go for it!
On the other hand, I really don't think that its worth swapping, the diferences in power between the 2 are minimal. But, if you can do it for cheap, go for it!