Does anyone know the major differences between an 06 and 07 and 08 5.4L 4x4?

Different suspension? Axles? Horsepower?

I am looking to pick up another truck and I was wondering what changed that might make me decide on one year or another?

 

mechanically identical, they claim to have fixed the plug issues in the '08 models, but i still wouldn't risk it by waiting til 100k. both 07's/08's have the same power rating, etc