5proms

Robert, sorry I made some bad assumptions about your 17 premium. 3000rpm at 65 is a little high for sustained cruise like you said. It’s a shame the 5.3, 6 speed combo doesn’t work better together for towing. Our 05 Yukon Xl with the 5.3 only had the 4 speed and in 3rd at 65mph it was spinning at 2500rpm, pulled the Airstream well in the flat, Only needed 2nd to maintain speed up some hills. I highly recommend the 6.2l ecotec with the 10 speed. Buckets of torque starting at 2000rpm and plenty of gear choices for towing. Better fuel economy than our old 5.3 if you can believe that!

With a 10 speed tranny, (which I’m assuming you have) you don’t need to change the rear axle. Put it in manual and select the gear that keeps the engine in the ‘sweet spot’. We have the 8 speed in our ‘15 ESV and we pull a 7000 lb, 32’ Airstream. I keep it in 6, and at 65 mph, it’s about 2200 rpm which is right in the torque curve and steady transmission temps at 175. It doesn’t shift much at all while cruising which is what generates excess heat for automatic transmissions. MPG between 11-13.