Steering Caster Correctors, Scout II
Scout II's (up till 1980) came from the factory with 0 degrees of caster. Caster is what enables your truck to track straight on the highway. It also affect the return to center of the steering after a turn. Finally in 1980, the Scout II had 2 degrees of caster built in. Before, you had 3 choices to get caster on your Scout II:
Twist your axles. Having your axles twisted is expensive, around $250 + just for turning the housing. If it is not done correctly, it can be unsafe, or the angles on each side may not even be the same.
Install degree shims between your axle pad and the leaf springs. Installing deg shims between your axle pads and your springs will deteriorate your pinion angle the same amount as the shim, possibly leading to a shorter U-Joint life and driveline vibration.
Find and install a front axle from an 1980 Scout II. Finding and installing an 1980 Scout II front axle can be expensive, (if you can find one), and you may have to change out the differential gears, if they don't match your existing rear ring and pinion gears.
Now you can use Caster Correctors to solve your highway wandering problem.
Caster Corrector Installation Tool