Keith, I suspect that peg is for the "silent door latch" I see described in
the manual for my '75 Westfalia.  It's just a horizontally mounted handle.
The manual says "You can now close the sliding door silently without
slamming it shut.  Slide the door forward until you can grab the rear door
handle.  Pull the handle to close the sliding door."

Handy if you're headed out to answer nature's call and don't want to wake
the family, or maybe if you're stuck camping in one of those parking lots
they try to call campgrounds these days and are trying to be considerate.

Randy, Carla & Anna Huyck
Lacey, WA
'75 Rustfalia
'79 Mercedes 300D
'85 Vanagon GL
'90 Fox GL