Mine I'm usally running at around 72-75 mph. It does just fine at 80 but gets noisy and MPG drops off. I'm running at about 1700 rpms at 72 mph. It gets close to 2000 rpms around 80 mph.

 

I have a 1993 W250 and it really likes 65 MPH. But I drive it 72-75 MPH and it does OK. Its a big ole truck and it wasn't built to be a freeway cruiser. I can load the bed down with hardwood and drive it from here to Virginia and it doesn't know its back there. I can chain a pine tree to it and drag it uphill on dirt roads on a 6% grade and the only thing I feel is a little rear end steering. When I want to drive 80MPH for hours I just drive the 2001 Cherokee. Fuel economy wise the Dodge does way better for its weight and the work its doing. The Dodge is also very good in traffic because at idle it doesn't use much fuel at all.

Regards,
Brian

 

That's about what I see. DBF