lowering rear 2001 1500 4x4 Z71

I just purchased a 2001 silverado reg cab stepside 4x4 Z71 and the rear end is 2 1/2 inches higher then the front. I would like to drop the rear end 2 inches. I noticed that their are 2 1/4 inch steel spacers between the leaf springs and the rear axle pads. Are these spacers factory or did the previous owner add these.
I can remove these and use shorter u-bolts. Has anyone tried this?
Does any one see any problems with this? I dont do any towing or haul heavy loads.

thanks
Steve

Why would you lower the rear, rather than raise the front. I have never heard of anyone wanting a lower 4x4

Those are factory parts. The Silverados come from the factory 2-2.5" higher in the rear of both the 2x4s and the 4x4s. They do this to help the truck tow and hall heavier loads without overloading on the wheels. The easiest way to drop the truck level and still retain your hauling capabilities is to get an aftermarket 2" shackle kit. They usually cost between $30-50. These will replace your factory shackles and they are a very easy install. I'm posting a link to some good quality shackles here. You can remove the things you were talking about, but it isn't recommended if you haul anything with your truck.

http://accessory-center.com/series.plx/30/1358/1127

These will drop your truck down level and still allow you to have stock towing/hauling abilities.