Exhaust or jake brake or neither?

Often the distinguishing factor is the button that turns on the brake device. Most often the exhaust brake is an on/off button, and if there is a two stage button it is a Jake (Jacobson) brake. Both are intended to slow up the vehicle and I would encourage you to get acquainted with this device. Generally, we have found the Jake to be more aggressive even in the less aggressive mode in slowing the vehicle up. I have taught RV safe driving in just about every brand, size, or vintage RV motor home. You have two valuable tools to slow you up coming down a mountain as an example. The Allison 3000 can take some speed off by just shifting down. You can't break the transmission because the computer logic won't let you Do use the transmission down and/or the engine braking devices. They will help control the speed on a down hill but you will most likely still have to use the brake to keep you from losing control. One other note, you can leave either of the engine retarders on all the time. Enjoy your RV and safe driving!