They have a governor, and will not rev much over 3500 rpm. And yes, they are slow with no turbo.

 

Good to know. I'd never seen anything idle at 250 RPMs before (even I idle faster than that! ) and didn't know if that was normal!

Guy I know is trying to sell me a 2000 GMC with 235k on it. I'm resisting. I figure there's good reasons why we see a lot more old Fords than any other truck.

 

250 rpms is not normal, it's more like 500rpm. But since you said it would not rev much past 2xxx, then like someone else said, I would suspect the factory tach was not right.

 

It sounded to me like it was actually turning over that slow, and like the tach was probably reporting it accurately (at 2500 it felt about the same rev-wise as my old truck does at that RPM). Guy said it always ran slow like that. At 20-30mph on the flat it was around 1000. It upshifted real early compared to my gas truck, was in 3rd by 20-25mph. (Transmission seemed smooth, tho.)

Well, I guess you can't accuse it of being overworked.