Yeah an NV4500 to replace the about ready to grenade NP435. In all honesty I didn't do the swap for fuel mileage, it was my original intention when I started gathering parts for it because I drove a lot of highway miles in FL. Here, maybe 70 highway miles a month, so I knew it wasn't going to be a drastic change. The truck spends most of it's time around here under 30 MPH. The upside is I can actually drive it at 70 now, my ears don't ring for two weeks after I drive it and I now have A/C. So that figure is with A/C on that the truck never had before.