Hi Chuck & Lynn:
I don't know of any fixed base source for the Bargman #9
tail light plastic lens. Generally, the older the Airstream
trailer is, the more you must be a good scrounger to find
the parts to restore it. Over the past 5 years, I found two
Bargman #9 plastic lens in vendor's "junk parts" boxes at
auto swap meets, but it took a lot of time, walking and
scrounging. Those lens were traded to people who were
restoring trailers than took those lenses, and I don't have
them anymore. Others might have squirreled some away and
be willing to swap or sell them.
While looking for the #9s', you also might keep your eye
open for old Signal Stat Acrlystat 4" plastic lens that have
the same general appearance. I've never matched up the 4
screw holes, but they look to be the same distance apart, so
some old red Acrylstats might fit and work. The dull
plastic lens might be shined up with some fine polish. Happy
Hunting!
Fred Coldwell