Hi I am in the process of piecing together items for my first ls conversion. I found a 2500 van with a 4.8 that runs good and the cost is very low so I am debating using this vehicle for the engine, trans, gas pedal, computer and harness. What is the difference between a 4.8 5.3 and 6.0 computer and harness? Is it just the factory tune? So if down the road I wanted to pull the 4.8 and replace it with a 6.0 would I need a different tune or anything else? Thanks.