Lowering a '72 GMC ???'s

[ablack]

I'm sure this has been asked a few times before around here, but I can't seem to find the answer I am looking for, so I figured I'd ask again. I'm working on a rebuild of my '72 GMC and I'm ready to do the rear suspension, and I want to lower the truck and am looking to see what the options are. I'm sure I can get some springs that do it, and I've seen mention of a "lowering block" (although this makes no sense as I also have a Toyota 4x4 and my only experience with blocks is to put them in to GAIN height). Any information/opinions on my choices would be gratefully received.

Thanks guys!

Alan
Elk Grove, CA
'72 GMC