I need some advise on a truck I'm looking at. It is a 2007 (new body stle) Chevy 2500HD ext cab, 4x4, LS model with the 6.0L gas engine. Its got 51000 miles on it and seems to run very nice (I did test drive for a bit, up to highway speeds). It looks very well taken care of and was rust proofed with Z-Bart twice (again about 2-3 weeks ago). What things do I need to look for with these trucks? Any known problems or anything to look for specifically? I need help fast!!!