What's the cap on the right rear panel in this photo of a SA van?
<http://members.cruzio.com/~cikasper/sa/pics/carrier.jpg>

Looks similar to a gas tank filler cap, but...

Water? Feed for the chipmunks?

Dave
--
Dave Carpenter

Whatever you wish for me,
May you have twice as much.

"Sometimes I think we're alone in the universe, and sometimes I think
we're not. In either case the idea is quite staggering." -- Arthur C.
Clarke