2nd Row Rear Seat Bracket

[HO455]

The bolt holes should line up with the square nuts on the bottom bracket. (Circled in green in the photo.) I'm not sure as to the use of the one I circled in purple.

The factory used the welded nuts so you wouldn't have to crawl near the truck to remove the seat and to save time on the assembly line. Although the latter reason was the important one for them.

My 67 had a separate bracket (on the left in the photo) which I believe was a one year thing but you can see the 4 nuts in a row for the seat on the right side, with two others on the left that I can't account for.

I'm not 100 percent sure but I believe there was a different lower plate for 2 row and 3 row Burbans. Maybe Richard2717 will chime in here with the answer to that.