Update: My mechanic finally found the problem. My right rear leaf spring is saggy. It's making my front, left corner lift up. GM has discontinued those leaf springs, so he's recommending a specialty shop. I called them for an estimate, and they say it's $1,200. Ugh.

 

check out SDtrucksprings.com They appear to have them for these blazers for around $100-$150 each. I would recommend replacing them in pairs so you don't have one side higher than the other.

 

just get an add a leaf kit.

 

I definitely agree with ChukNTruck that if you replace one, you should replace the other. If you have the measurements of the factory springs there's a number of places online where you can order affordable replacements. The other option is that some spring shops can re-arch your existing springs, putting them back to a factory height.