[Huck]

The body is everything on Blazers and Jimmy's. Look at the rear floor where it bolts to the inner quarter panels "UNDER the carpet or mats!!". check for bondo on the windshield inner frame above the sun visors. There are long metal "torque boxes" that run parallel to the door rockers --they support the body with the top off. You want them solid!!
99% of Blazers and Jimmy's rust at the bottom of the B pillar--that is the vertical section just behind the door--the leading edge or the rear quarters--especially the lower corner.
At $800. if it is fairly solid you are fine.
--auto or stick (auto more desireable to some) Huck