Its what swartlkk said. soa = spring over axle & sfa = solid front axle. looks like there might be a body lift, probably 2" considering the year it is, but your leaf springs in the rear have been swapped to over axle, and looks like some pretty big shackles. in the front, you have a solid axle, which, isnt factory on blazers.

Since our blazers look almost the same, i believe mine is higher judging by the frame height in middle. looks like you have a smaller tires. the bumper in the front may cause you an issue, i have factory bumper and by pa law, is actually illegal. Most inspection stations and cops know the max height, which is based off the full size trucks. mine is barely under those measurements, so you may be ok. if the measure off the frame which is next if bumper is out of spec due to alterations. This is just my interpretation. i put our blazers into one image to give you an idea, i tried scaling them to both same size based off windows.