I have a Detroit in a 2019. I understand from other driver’s that the Cummins are gutless and the engine brake isn’t all that great. Remember though, these boy’s are pulling triples. It’s not Kansas either. There’s a couple of mountain passes. Personally I like my tractor, it does the job. I do wish I had more power though. My engine brake does a great job going down my mountain. Barely touch the brakes. Old School, we were told how to use the transmission, terrain and engine to hold your speed. Billy and some of the other senior drivers can remember that OD never had engine brakes. You young pups would be smoking them brakes all the time.