Well after two trips towing with my stock 5.7L DC I took the advice of this forum and I installed a set of Air Lift bags. What a difference!
We pulled our fiver up to Shaver Lake which is about 60 miles from where I live and is at an altitude of about 6,000 feet.
There are several very steep and winding roads and I am happy to report that the truck performed very well. The grades are anywhere from 6% to 11% and the truck didn't struggle at all. The tranny and coolant temp gauges stay right at dead center the entire trip.
I have been 'playing' with the Prodigy brake controller, trying to get it set up just right, and I think I finally have it where I wanted.
I had to set the voltage at 12 with the boost set to B1. This seems to be the magic combination for my trailer.
The Air Lift bags I installed really helped stabilize the rear of the truck and all but stopped the 'bounce' I had experienced on previous trips.
I inflated the bags to 30lbs before hitch up and as you can see by the attached pictures there is no sag.
A big THANK YOU to d-lo and the other who convinced me to order the bags.
Bill