....well remember, your trailer also has brakes...that too will help....Your under weight on your trucks specs...I'd say use your T/H option and down shift on the shifter when going down a steep hill..The allison with it's grade braking, along with the manual downshifting you can do along with the brakes on your trailer ought to be enough. "IF" you really want to add an exhaust brake, make sure you purchase one that is adaptable to your D/A combo...I know Banks use to make one for the D/A and I understand it was a pretty good one.
But again, you're not overweight, you have T/H, manual downshifter, the Allison grade braking and you have the brakes on your trailer...unless you want to spend more money, I think you will be ok...but it's more an opinion thing with me...
