Doesn't the abs prevent the rear brakes from locking up, even w/ full braking power? The only thing this might effect is in a hard stop the Abs will activate sooner.
My ABS is a joke. My rears lock up all the time, fronts too. On an F350 I used to have it had the same setup. I removed the valve, lever, etc. . and put a regular T fitting in place of that mess and all the brake problems went away. Ran it like that for years, loaded, overloaded, empty, towing, and plowing, never a problem.
I know... it was a Ford these are Dodge, but the principle is the same.
just mt . 02