I would go with the manual tranny even though the 68RE is a nice tranny. If your sold on the 6.7 then get the DPF/EGR Delete kit for sure or your mileage will be terrible. Also, I think the 4.10 gears are unnecessary. 3.73 will be just fine. 38K is steep right now. Look in the SE TX area and you can find a better deal. I don't know where your located but if you can find a cheaper deal then it may be worth it. Make sure you go into the buying process willing to back out. As long as you have the upper hand you'll be okay. Set a max price you will pay and don't budge.