Hey Lyle...sounds like you are due for a new hitch! May as well get the puck version, when you order that new GM. Compared to a new 3500 diesel cost, the hitch will just be change out of pocket! :)
You do know those clip-on leveling spring pins can easily be adjusted to change lift pressure to head. If not tightened properly, the spring may have rotated, losing head tension. My hitch with spring, is 8 yrs old now, and holds head up fine, never needing adjustment.
Maybe Craigs hitch is old, or purchased used (spring never installed)?
Did the early version Companions not come with the leveler?
Jerry