will they fit there is someone selling 19 rims and tires and he said they measure 33 inches but he is not sure if i had to lift the truck its a stock 03 gmc sierra 3500

I don't have 19" rims on my dually, but I do have 255/85/16 tires on my stock rims which happen to measure 33.3". I do have spacers on the rear so the duals don't rub, but have done nothing else. These tires are the BFG KM2s so the tread is purty aggressive. When I turn the wheel all the way to lock psoition while putting the truck on a bind...curb, hill, etc. the tire will slightly rub on the front plastic valance. I've been running them now for about 10,000 miles and no other problems.....knock on wood. I think you would be ok if those tires aren't really wide. Worst case you might need to crank the front torsion bars a tad, or remove a bit of the plastic on the front.

On Edit: I think the 19" rims have enough offset to prevent the duals from rubbing, but you would have to verify that on your application.

Yes, you will have to crank the torsion bars and make sure the tires on the rear don't rub with a load.