IIRC, outside mirrors were shipped to the dealer for
installation. They ended up being put in several places at
the customer's or dealer's discretion. I've seen "factory"
mirrors on the doors and fenders of both '55 and '56.
Speaking of right, the right mirror usually is worthless on
this vintage. There's no right answer, unlike "lesser"
models such as Dodge which had one spot for the mirrors that
actually worked.
--Roger van Hoy, '55 DeSoto, '58 DeSoto, '42 DeSoto, '66
Plymouth, '81 Imperial, Washougal, WA