Check the frame instead of the body. If frame same, then body mount or rad mount. If frame not, then cocked front stabilizer bar or unequal tie-rod ends length, micro-bent A-arm (doesn't take much to hurt an A-arm a few degrees if you hit something and you'll never catch it visually). Spring isolator squished out at top (but pretty hard since they are pretty hard rubber and only would account for like an 1/8" drop). Springs usually sack equally - mine did . . . ALOT, but an outright fatigued one might drop quick. HTH