Were 1.5 tons ever equipped with shocks? I don't think so. Even a slight bit of looseness in the tie rod ends or a poorly adjusted steering gear preload will cause "shimmy" at certain speeds, and a tire a little out of balance will make it noticeably worse. Unless you've driven far enough to get the tires warmed up fully (10 miles, maybe?) you've probably got flat spots in the tread. These old rigs were designed to haul max gross weight loads (or more likely big overloads) around all day at 45 MPH . Trying to keep up with traffic on the highway without a load on the bed makes them pretty uncomfortable to drive. "You really can make a silk purse out of a sow's ear, but it makes the pig look funny and it doesn't hear very well afterwards!"
Jerry
