changing from 5 lug to 6 lug axles

[dumpedv8]

im interested in changing my 1997 silverado 1500 2wd from a five lug to a 6 lug to run the silverado ss 20 inch wheels. ive looked at getting adapters but they a 2.2 inches thick and that is just way to thick for me to be able to lower the truck onto them. any advice you could give on how hard it is to swap or if even possible would be greatly appriciated.