Truck vibrating sometimes when jakes are on

[Shokar92]

Hi I have 2014 Peterbilt and last couple weeks when the jakes are turned on the truck sometimes starts vibrating like its driving on rough terrain. It doesn't always happen. The truck has around 690,000 Miles with a ISX15 485 HP engine. In the last couple months I had the cover open because I had coolant in the diesel filters and since repaired that with the new fix from cummins by adding the rings to each injector cup ran great for a couple month and now this issue came up also this truck doesn't have DPF its used from farm activity..