We are going to run the vin#. I am also goin take a freind with more experiance master mechanic for 30 some years. It doesn't make sence from all the other claims I've read. FYI corner station this morning 87 gas 3.04 diesel 3.89 better get some pretty dang good milage to justify that. I think I can buy e85 for 2 bucks. Yes I loose about %20 . When you crunch the numbers that 6 liter looks better and better all the time. I don't want to start a war just I am going to by a truck in the next few months and I am open to anything that works best. Heck I even thought about a ford for about 5 minutes. Iv'e always had GM and been very pleased with there products so I am staying with the GM line.