WBCCI numbers are registered to the owner, not the trailer, so history by number can be a mixed bag. Numbers are reassigned if an owner leaves the WBCCI, usually after a couple years. Any documents/badges/decals related to rallies can help you build a history.
WBCCI number 502 is a very early number. My number, 1996, was first registered in the fall of 1957
, but I can't confirm that owner had my trailer. All the WBCCI decals/badges/photo I found in the trailer relate to the second person 1996 was registered to from Arizona. The number was originally given to an Iowa resident.
The serial number 7719 would match a 54 Flying Cloud built in CA. Keep in mind this data is believed to be correct, but records are sketchy and hard to confirm unless you have documentation from the original buyer. The attached link should help you confirm if its a Flying Cloud by length, layout and window placement.
for general reference to all models use:
Send an email to firstname.lastname@example.org
and the historian will see what information is available on your number and go from there. Send as much information that you can, but don't expect miracles.
good luck, look forward to seeing your progress. Include lots of photos and the forum will support you as much as we can.