I tried out a 91 F150 XLT tonight, and passed on it because it had a noticeable side to side wobble at most speeds.

I really liked the truck other than that (4.6 six /manual), and I wonder if anybody has any thoughts on what it might be.

Didn't seem to shake the steering wheel, and it seemed better when braking( I think). Was not severe, but it was definitely noticeable.

Any comments appreciated,

Thanks

 

Badly worn tyre, tyre out of shape, bent wheel rim, worn suspension bushes, worn steering bushes, worn steering box, or in need of alignment.

 

Don't forget ball joints. Just did ball joints and radius arm bushings in my wife's 91 Explorer and solved the same problem.

 

Axle pivot bushings since you didn't notice any vibration.