@Powerhouse Ranch,
Besides the width which is mostly a 2", it's the spring pack, how many? Because the bolt can't be flopping on top of the pack, it's got to sit right on top of the top spring, or it'll slip. I did a partial look at Speedway Motors, Classic Industries, even J.C. Whitney and Ebay to. I've really not seen them very often. A lot of people need to replace the ones they've got because the bolt and sleeve is messed up, worn so bad the whole clip is loose and rattling, and they need to replace them themselves. But I'll tell you what, a lot of times you'd be surprised, the GMC dealer may have them. Check and see if you local GMC dealer has them, and you might also be surprised, they might be cheaper than you think.
I don't know how much new stuff I bought for my C10 when I was rebuilding it, my local Chevy dealer had most body parts cheap. They had the whole front clip, hood and all for really a cheap price. The reason I didn't get the whole truck from them is they stopped making some of the body parts, like the bed floor. Otherwise I would have bought the entire truck from them...new. Wouldn't that have been cool!!