This was first noticed at 30K two months ago. After warming up, a shuddering at about 35 mph that gets more pronounced while driving. Stop, start, comes right back. Thinking it was a stuck E-brake, pulled the E-brake levers back, went away. I thought the fix was then, don't use the E-brake.

Also, slight brake rotor tick that comes and goes since 25K, which I can live with.

Today, rolling down the road, 40 mph, the same pulsing vibration starts up. I have not been using E-brake, so I was surprized. As it got worse, more harsh, I pulled the gear into neutral to see if it was drive train or tranny. This had no effect, the vibration continued and as the speed went down, so did the pulsing until I pulled over. I did the same, pull the E-brake levers back, as that is the only thing that worked previously. Took off and experienced nothing.

Touched all rotors at home, only the left front seemed unusally hot. The front right and the rears were touchable without burning my fingers.

I like to have a good idea of WTH I'm facing before I go in and blow 1500 dollars on something my truck doesn't need.

Tires have been rotated on schedule and are balanced. LS has always worked and I've never abused this truck. On the slab on cc I average over 20 mpg. In the winter in town it falls off to 15.5 mpg. Pulled a trailer once.

 

May want to check your brake fluid level. I dont know if it would have that type of effect but just an idea.