Hello, I'm looking at a 2013 yukon with the 6.2 engine. I have recently test drove a 2012 yukon denali, for several weeks, that belongs to my boss. He owns a used car sales. The 12 model has the afm deleted with long tube headers, head studs, and what seems like aftermarket cam. It runs good but has little body damage and high miles. So, looking at the 2013, I'd like to buy it and do the upgrades to it. It has 140,??? Mile on it. What should I look for to determine if it is healthy and still worth putting some money and effort into? Any thoughts?