Robert, why don't you contact Gale Banks Engineering? I've had a Banks exhaust brake on my '03 F-250 since it was brand new. It works like a charm while pulling my 35' Montana fifth wheel trailer.
We are doing a trip to Alberta in late June to attend the Calgary Stampede, and then through Montana, Idaho, and Colorado. Wouldn't do the trip with out the exhaust brake.
Contact Banks at
www.bankspower.com. I am sure they can assist you on your needs.
Jim McClure