If the retainer was a allen head screw then the handle is from a 60/70s era Dodge product .
Looks exactly the same as my 68 Coronet and 73 Sportsman van.
EDIT: A quick internet search for Dodge manual window crank handle , turned up these .
Doesn't look exact but I'll keep looking .
Getting and invalid file message so I can't post the downloaded pictures
I'll be back.