I have a similar truck on 36x12.5-16.5 RT/II's using GM 16.5" wheels. Pictures are on my CarDomain site that is linked to through the www button under my posts.
When you get these on check your steering stops. I found out my tires could hit my drag link and destroyed the forward drag link end. Whoops. One 2" Grade 8 3/8" fine thread bolt later the problem is fixed...except for the drag link.
How stiff are the springs still?
Mine don't move much so the tires don't get all that close to the fenders. Just a little trim to the front fenders on each side and the 36's fit good with no lift. I don't wheel the piss out of it though so I'd imagine if I went out and purposely got it crossed up and flexing hard I might be able to make it tag the fenders.
Lifting it is kind of a paradox. MOST companies don't make lift kits for 1 ton trucks, only the vastly more common 1/2 tons and 3/4 tons. The front springs would bolt right in...but having a lower weight rating they would allow the tire to flex more and therefore go into the fenders easier. You have to look for heavy rated springs. I know Superlift makes lift kits specifically for the 1 tons but they aren't my favorite company for other reasons.
In the rear the 1 tons have 56" long 3" wide springs compared to most 1/2 and 3/4 tons' 52" long 2.5" wide rear springs. Remember that before you buy rear springs meant for a lower weight truck. Just a heads up from mistakes others have made.
Consider a shackle flip for the rear and then only lift springs for the front.
That is what I will do eventually. 3" front springs, 2.5" ORD rear shackle flip and 1" zero rate, and trimming whatever else is necessary.
Oh yeah, as far as balancing these check out
http://www.innovativebalancing.com . I use their beads in my vehicles and they work great. I had POUNDS of weights on the tires that seem, so far, to have been replaced with 10 ounces of their beads in each tire. So far, so good.
