torsion bar identification?

i have installed 31" tires, re arched the rear leafs, but have a small problem with the torsion bars, front is saging and the adjuster bolts on the torsions are not equal, I get one set of stock one set of thicker torsion bars, the stock ones have #503 and #504 on l and r side, also found  a set, which is 281L and 282R numbrs, same ends as stock ones (1,5" hexagonal) but thicker/have more meat on the body.
Thought, they would be harder or H-D ones.
I have checked the offradtechs article about the torsion bars and inspected the GM# list but there no match with the stock ones and the thick ones, what is 503-503 and 281-282 numbers on the ends? rates etc?
 
thanks.

Since theres no info on the torsion bar identification, me and a friend of mine installed thick torsion bars and lifted the truck.
 
Update:
The front is stiffer now, ( just 30 miles road test way back home) .
 
Im not sure if this stiffness is caused by bars itself or cranking. BTW driver side key has cavitation on the adjusting bolt place, i have replaced both adjusting bolts with the longer ones.

did you get anymore lift out of them??

Yes i have cranked them 2". I had my 31" bf all terrains installed, need to crank it up.

In general theory bigger is always better, more heavy duty