Kurt, while you may be able to find cranks and arms at an Airstream dealer
that has been around for 40 years (Ace Fogdall in Cedar Falls, Iowa) you
would have to be extreemly get lucky to find a window frame. Your best bet
for that would be a trailer that is too far gone to restore. However, most
likely you will need to purchase a new modern window and install it in the
old openings.
Scott