Big_mike_white

Our Fire Department has an 07 k5500 topkick with a crew cab. It has the 6.6 in it. I know they came with and exhaust brake but ours doesnt seem to have one. Is it something you can get programmed in from the computer or do you need to get aftermarket parts? I am trying to figure out how they retarder brakes worked as well. Any help would be appreciated.