My first 69 sb!

[bbcmudtruck]

I've been lurking on here for quite a while and figured I'd go ahead and introduce myself. I started out with a 72 blazer when I was sixteen and ended up junking it after many years of stupid young kid abuse. Now 14 years later I finally purchased my first short bed! I have been wanting one of these trucks since I could remember! The previous owner has done a lot of work on this truck prior to me buying it. The cab has been completely redone and is rust free. The motor runs great and is has a slick set of wheels and tires. Now the bad... It has a 90s style step side bed on it and it is eating me alive! I've come to the conclusion that I should probably just buy a new bed and assemble it rather than try to find and impossible short box in great shape. Blah blah blah etc.. Now I need some help in figuring out just what I have exactly. It is lowered however I don't think it was done correctly. The ride is absolutely horrible and it bottoms out on the smallest of bumps. Also, the rear has factory leaf springs, but the frame has not been cut. Does that make it a GMC rather than a chevy? What all do you guys need to know to help me figure out whats been done?