Bestop used to market similar boxes, called "Roughrider" storage boxes. I had a set in my CJ-7. However, I don't think the boxes you purchased are the Bestop product - they look too narrow.
from the scratched in date appears to be made on March 18, 2000 in High density polyethylene...could they be a prototype that never made it into production?
I'll get some better full pics when I get home, they have a bracket that tucks under the lip for mounting the hardtop and screw holes that match to bolt it in, even clearanced for the soft top arms. For $40 for the pair I couldn't pass.