About seven years ago I had a 2001 Dodge 4X4 3500 with auto transmission and 3.73 gear. I added a banks exhaust brake and it did work somewhat but I ended up adding a transmission controller device that would lock up the torque converter when the exhaust brake was applied and then the exhaust brake worked very well. I pulled a heavy King of the Road fifth wheel and I think it was worth the investment. Having done this, my opinion: without locking up the transmission torque converter the exhaust brake would be a poor investment.
Bob, Sandi & Marmaduke the Big Pug
SW OREGON 2004 Journey 39K, 330 Cat
If towing: a 2006 Mini Cooper or 1995 Wrangler