Most steering stabilizers are for a shimmy caused by out of balance tires or a worn drag link/tie rod ball socket.

Stock suspension, straight front axle with leaf springs?? Stock springs?? Power steering, yes/no?? Stock tires and rims or some aftermarket?? Did your alignment shop give you a receipt with a print out of what spec's it was set too?? All 3 checked, toe, caster, camber??

To correct Caster on leaf spring suspension, tapered shims are used between the spring and axle saddle to tip the axle forward or rearward to the spec.

From post #5
" Caster has all to do with the steering returning to straight ahead. And not have to correct steering that constantly goes left and right on it's own."

If your problem was normal for all 79 F-250 4X4's there would be hundreds of writings, complaints about it, you need to turn over every stone, so to say, to get to the bottom of Your problem. Some thing being addressed is not right.
Cap