Assuming legal ownership of two gasoline gmt800s and wanting to end up with clean title and VINs matching across all paperwork and physical instances, what are the big picture issues in majors swaps? For example VIN/Reg/Title, computerized parts (pcm,bcm,instrument cluster, etc). I understand sticking within 99-02, or sticking within 03-07 will go a long way to reducing the complexity. Apart from the general idea of having the two 800 as similar as possible, what major pitfalls and headaches can be avoided? and how?