Well How bout that. Another Minnesota boy. haha I'm also from Minnesota.
Anyway, High milage is okay if he took care of the vehicle and there are documents to prove it. Even if they aren't it depends on who the person is.
177k is low mileage to me. As long as you can take it for a drive and look really good at it then it should be good.
But I'm gonna tell you now. Engines are easy. Tranmissions are hard. To fix that is. Look at ANY leaks, that might be a problem later on. Also, take a look at the engine oil cooler lines, make sure they aren't leaking. Same goes for the Transmission lines. Look at the color of the oil and whatnot to see if you gotta change it soon. Ask the guy if he has been using synthetic oil or conventional. Always good to know.
Ask him when basic things have been changed out, examples; water pump, serp belt, power steering pump, fluids, spark plugs, wires, cap, rotor... etc. Ask him these things and maybe even documentation. I didnt. And I had to change the water pump within a week. Same goes for the power steeing pump and a few sensors.
Also, during the test drive. Before you take off crank up the radio a little. make sure no speakers are blown. But when you are driving it, make sure that radio is off. Listen to every little noise that the truck makes.
just a few things. Always ALWAYS listen to your gut. If for any reason it doesn't feel right. Walk. Cause you can find PLENTY of trucks with low mileage.