[VAC] Lock Cylinders

[Ed]

Where can I find a key cylinder to replace the one in my entrance door
to a 1969 27' International?  My locksmith is stumped,  My airstream
dealer is stumped,  and the guys who bought all the old Airstream stock
say "no way, but I can buy a whole mechanism for $550.  Before I take
the low road and put in a conventional free standing deadbolt, Anybody
got a better idea?
            Ed Farrell