Brake problems on 92 silverado

[myclone]

That really sounds like steering parts are on their way out. The last truck I did was the 93 FSECLB that had a worn out drag link. At about 30mph if you were going straight it would start to shake and keep on shaking till about 45-ish. You could stab the brake pedal real hard and it would stop most of the time or yank the steering wheel one way or the other and it would stop (most of the time). IMO at a particular speed one or both of the front wheels are doing the same thing the casters on a shopping cart do when they wobble. Hard to explain in text but it made sense to me once I thought about it a while.

Easiest way to tell is to jack the truck up and sit the front wheels on ramps/blocks so they are supporting the trucks weight. Have a bud turn the steering wheel until he feels resistance then go back the other way until he hits resistance then repeat (engine off BTW). Have him continually work the wheel back and forth while you look over the steering linkage for excessive slop. Id put money on you finding one or more really worn out components.

You wont find bad ball joints this way but I bet you find fragged steering stuff before you get to them anyways.

HTH