Too much work to make an 05-06 work. Ideally you'd need to do what I did in my 06 Trailblazer and my LS3 engine which is remove the crank, have the engine shop press off the old crank reluctor wheel, buy the alignment tool from I forget where for $100, press on the 07+ reluctor wheel, and reinstall the crank. Then you need to swap the cam gear to the 4x pickup. If you have two engines, just have the one engine rebuilt, is my advice