Aint it though? Talked to a guy a couple of months ago with a ProStar and a 475 ISX. Said he was getting 9 loaded and 9.8 mty. Sure hate to call a guy a liar but dangit, I don't think that truck would do it behind a wrecker!

I discovered something interesting about my truck today. My odometer has been lying since I bought the truck in 2007 and I finally decided to look into this. I stopped at an International dealer in Las Vegas, NV today and the guy discovered a HAND WRITTEN number on my rear differential, "3:53"! The plaque on the front axle - just as all the paperwork that came with the truck - still says, "3:73". No wonder my speedo was wrong! Which means I don't have to drive slow any more: 512 rev/mil X 3.53 X 0.73 = 1319 rpm at 60 mph. With 3.73 ratio it is 1394, and that's why I thought I had to drive at 57-58 mph to save fuel. From now on, I'm doing at least 60 mph.

When I was buying the truck, I was under full impression that the truck had 3:73 rears (that's what the salesperson represented to me).