Regarding bumping ads in the classifed forums, we've just installed a new (customized) add-on that will change the way ads are bumped to the top. Please refer to the post "Bumping Classifed Ads" for details.
The big open shape of the teardrop
the single rivet attachments
and the single bolts attaching to the fender
Schwinn rivet heads are smaller that others and almost hemispherical
Other makes are pretty flat
(with the exception of rivets on later 30's Colsons with flat braces )