In addition to many brick & mortar Airstream dealers, the only online
source I know of is InlandRV (http://www.inlandrv.com/parts/ for
pictures). They have the mechanism and the clips. The issue with their
clips is that they require InLand's stainless steel window pane edging
kits. I've got to give Andy credit in this case, the kits are very
nice, and are almost a necessity when replacing a broken Corning glass
window with Acrylic sheet material, as it gives the 1966-1968 windows a
nice finished edge, strength and weight to keep them from flapping in
the wind.
Best of luck,
RJ
VintageAirstream.com