Woog-
Do a search and you'll find lots of insight and archived photos. For safety sake in a truck with latches that do not keep the doors closed in a crash, this is an important feature. Visit Juliano's or Gem Street rods for components. Juliano's sells a backing plate you can weld in for the strongest pillar attachment.
In my '54 GMC, there is actually an existing hole for the D ring on the pillar (as noted, hidden by the rubber windlace). I will widen this to accept the D bolt and back it to avoid pull-out during a crash. The seat is out as of last weekend and I am putting these in as soon as possible (if I could find the time)!
