do you have a part number for the arms and blades?  Stephen Allen's
shows some "unidentified" arms on their web site.  (I checked there for
you because they are reproing some of the later wiper parts)

nate

The '41/'42 Champs used the same arms and blades as the M5 trucks.  The
replacement arm had a Stude service part number of S-614.  These were
adjustable length, but they are no longer available.  The correct length of
the arm is 9-1/2" from the pivot center to the tip of the arm where it
engages the blade.  The blade length is 9".

Picture at http://www.studegarage.com/images/other/wiper_arm_blade_m5.jpg

The arms from a 1941-48 Ford are very close, just a little longer.  The Ford
part numbers for these are 11A-17526 (right) and 11A-17527 (left).  You will
need to carefully remove the tips from the arms, cut the arm back with a
hacksaw and drill a new locking hole, then re-install the tip.  Most dealers
in early Ford parts have these arms.  One source is Mac's Antique Auto Parts
(http://www.macsautoparts.com).  Price is $15.  The 9" blades are Ford part
51A-17528, $3.45.  Strangely, I think these arms and blades also fit Shelby
Cobras!

There must be a 9-1/2" arm available to avoid the trimming, but I haven't
found one yet.