Mine had 1 bolt/1 stud per side.

Run to A/Z (or other parts store)
Get (4)M10x1.50 x50mm bolts (full-threaded) Dorman #780-550 (2pack)

Put floorjack under center of crossmember.
Remove hardware from ONE side.
Drop floorjack about 2-3"
get a small monkey-wrench on the stud. Its a double-threaded stud. Will take a bit of elbow grease.
The upper portion of the stud is also a M10 thread.

Put any spacers you need.
Mine started out w/no spacers--couldn't even move 2mph w/o nasty shake.
NOW 3/4" drop and only have minor vibes on hard acceleration.

 

Right, it also helps to use a dremel or grinder and grind two flat sides on the stud so the wrench can grip. The heat generated from this grinding loosens the rust-weld.

 

Plasma!!!

 

NO. No Plasma.

I, personally didn't have any trouble using a monkey wrench BUT like suggested, a dremel to make flats does help and the heat generated will aid in loosening the rust.

You want to thread it out...not totally anhilate it.

 

Hey Man, how did you get the upper bolt from your rear shackles out. On mine, there is no visible nut at the back, and mine turns without ever coming out. I noticed you said you couldn't remove yours in one of your posts. thanks

 

Pull on the bolt while turning it, the bolt threads will catch on another set of threads. The bolts just turning and turning because it's only half way out, the bolt it just turning in the center of the shackle!! Hope this helps