Here we go I think
http://www.steelerubber.com/door-alignment-pad-70-1821-71.In my parts price list(TM 10-1126)for the G506 trucks, of which mine is designated the G7105, it shows part #466836 Bumper Assy., L.H. Rear Door Dovetail (with pads part of the assembly I presume). Part #463145 Plate, Rear Door Bumper Wedge seems to me to be the part that engages with the #466836.
As an aside, the book shows Part #474884 Plate, Side Door Bumper Wedge (for all). Does that jive with the part # for the civvy trucks of that era? Just curious.
Well, I should have done a little more research to have the answer to that last question. Mark's previous post on this topic had a link that led to the wedge plate that does indicate Part #474884. So there !
