HTown_5.3

I did use washers. I cant remember exactly how thick they were but after bolting everything up the difference between the two sides was about 1mm. From what I have read it is very difficult to get them exactly centered. The issue only happens ever so often. Was thinking it could possibly be an issue with my master cylinder. I have the disk/drum brakes with a vacuum booster. The 4 piston calipers do take a lot more force to stop than the 2 pistons. I am wondering if a hydroboost conversion may help this issue.

Just did this swap on 2005 GMC sierra 4x4. Having issues with shuddering while braking at high speeds. After driving on the highway for a while I will go to step on the brakes, the brakes shudder and the steering wheel will violently shake. All air is bled from brakes and tires are balanced. Any ideas on what could be causing this issue?