Sounds like the truck was in an accident. No idea if you pulled the carfax, but it is really almost impossible to bend the rear axle without some sort of impact. Whether self inflicted (backing up into something really hard) or from an accident (rear end collision), but it sounds like that is what happened.
More to the point, a angled rear end collision sounds like what happened. The repair shop probably didn't have the equipment to measure rear axle angle and just repaired the rear bumper issues. I had this exact thing happen to my mother's Subaru back in the late 90's.
They give us the car back, swear it is fixed, and it just drove odd. I mean, odd. Found out the rear was out of whack and they had not detected it.
More to the point, a angled rear end collision sounds like what happened. The repair shop probably didn't have the equipment to measure rear axle angle and just repaired the rear bumper issues. I had this exact thing happen to my mother's Subaru back in the late 90's.
They give us the car back, swear it is fixed, and it just drove odd. I mean, odd. Found out the rear was out of whack and they had not detected it.