Considering it's a 21 year old truck from PA, nothing too major that wasn't expected. Exhaust leak, smog pump locked up, a few serpentine belts, a battery and solenoid here and there and a starter. I've had it for three years and put over two hundred thousand miles on her, that's got to count for something.
Like I said above, I've had this truck for three years, replaced quite a few parts due to rust and driving it like a sports car. I've never had a problem with this truck that wasn't either due to age or my own driving habits. I've owned at least thirteen vehicles since I started driving eight years ago and none have lasted even six months.
Gas mileage is a little lacking from such low gearing but is made up for in brute pulling power. It will almost lift the front end dropping the clutch with a full load and can spin the tires in every gear. I put a few thousand pounds of metal in the bed and was still able to start off in fourth gear.
As far as speed goes, I haven't had it over 110, it gets a little shaky, but I believe lowering it might make a difference. What it lacks in top speed it makes up for in low end torque. Never have I not been able to get someone of the line in this truck, even against the angry-bee-in-a-can-exhaust wielding rice burners.
Hate to break it to you, but my buddies modded 07 mustang gt can barely chirp the tires going into 3rd so I doubt your inline 6 heavy truck could manage that in all the gears.
If the gearing is low enough, he might be able to chirp the tires in all gears, by popping the clutch. These old pickups were made to be farm trucks and were geared low for pulling hay wagons, crawling through a foot of barnyard mud, and being loaded down with wood. Your buddy's Mustang is more geared for highway/general economy.
I'm only fifteen and I have this same exact truck. Bought it last year with 160.000 miles on it and the previous owner beat the crap out of this truck, and it is still running good. The only major thing I have had to replace is the fuel pump.
This truck is a workhorse. The first time we used it we put 1750 lbs. in the back, went around a corner in 3rd gear at 7mph, and didn't stall.
This is a beast of a truck. Ford should bring it back.
I have the same truck with an auto. transmission... It's the best vehicle I have ever had... my brother has the exact same as yours, and he burns them down in all four gears, so it is very possible..