damn you guys either have sh!tty gm's or something. i ran 35's on my c3500 cclb for 30k an never had any issues, even jumped it - it came 4ft off the ground and went for about 60ft- and have been running the 35's and suspension stuff off of it on my c2500 for 10k, even ran the 35's when the burb was bone stock. i know the 2500/3500 are a lil beefier, but not much.
as long as everything is maintained, lubed, checked, taken care of, aligned properly, etc. you shouldnt have any problems.
man dont be scared, you shouldn't have any problems.
i always check my spindles nuts and other front-end parts when i change the oil. has never failed me.
my only concern is that, iirc you have RC spindles, i have seen one break and heard of others doing the same so i would watch for cracks in all the 90* corners.