I believe the '06 has 4 injection events, the '04.5 and '05 has 3 I believe, and 2 for the '03-'04. I believe EFILive is only available for '06, personally, I'd look for an '06 just for that reason.
What if the truck is around 500 or 600 and u put it in 4x4 from a stop and stomp on it. Will anything break?
Ha, one of those questions where the real answer is "it depends." If you drive like an horny teenager, you can break anything. At 500 to 600 hp, you can break a lot of things. A stock transmission won't survive, you'll need a built transmission with a billet input shaft, 3 disc converter, and all the other goodies that go with it.
As for the 500-600 hp, it depends on they type of setup. You can make a truck that produces 500-600 hp, but there's a good chance that when you initially stomp on it and wait for the first few seconds, it'll be slower than a stock truck. Typically, the bigger the turbo, the slower the throttle response will become and the the low end torque will be reduced. You can run a small compound turbo setup for more low end torque, and more broken drivetrain components. If you power brake it, you can even destroy an expensive aftermarket transmission that has been properly built.
Are you looking to have this as your daily driver that can also win races? Or are you looking to make this as your toy and have something else as a DD? These things can be reliable when built right and driven with a level head. But with a lot of power, you can't expect a 7,500 lb truck to be bulletproof with 600 hp.