I bought this 91 F-150 about a year and a half ago with 166,000 miles on it. I have been so happy with it ever since. I live in Alaska and I'm out in the Bush (Wasilla/Willow) and I have done my fair share of off-roading with this truck, and it still runs and runs. I have not been too good to my truck but it has been very good to me. I now have over 177,800 miles on its powerful 300 inline 6. I don't even have a V8 and I'm loving the power that I get from this thing. It doesn't have the most HP in the world (145hp) but its torque is nice for a six cylinder (265 ft-lbs). I have never had the engine of transmisson rebuilt, or had any major work done. The owner before me also said he never had work done.
The power is amazing and I love that I get better gas mileage than most trucks (because of my inline 6). I get about 18 miles to the gallon, when most of my buddies with their V8s get like 14. That is a big difference when gas is $2.80 a gallon.
The ride quality could use a little work but its an older truck. I have found that with all the older trucks I've driven in the past. In comparison I have found the F-150 to have a much better ride.