Brake shake

[Festes]

Have a 84 c20, 3/4 ton. When I apply the brakes to slow down it shakes the truck. The steering wheel doesn’t seem to shake tho. Past experience is when the rotors are warped it shakes the steering wheel.

 

[1987 GMC Jimmy]

I agree that something should be felt in the steering wheel for warped rotors, but I’d look at the rear drums being out of round.

 

[Grit dog]

Any issue up front will generally be felt through the steering wheel.
But is it a sudden issue, like fine yesterday, shakes today, gradually worse? Does the truck shake or just the brakes pulse?
Could be warped drum or another issue with rear brakes. In my (way past, havent been rocking drum brakes on something that gets driven regularly for a long time) experience, warped drums were only a symptom of the trucks that got overloaded with trailers and really got the brakes abused. IMO, they don't warp or leave deposits like rotors which appear "warped" much more frequently than drums.