Yes, they do thread into the welded nuts on the sill area and the driveshaft tunnel. I'm trying to find a pair for a buddy so we can get his car on the road. He is about 1500 miles from me and is not very sharp mechanically.
The short bolts probably go on the outside attaching one belt. The center hump attachments probably need the longer bolts because of the center belts. (2 belts attached to the same bolt)
