I would think that one of the more graphically inclined people on this
newsgroup (Bondo?  Rick?) might have the font for the numbers, then you
could just print them out appropriately scaled, take the serial tag to
your local mall (yuck) and have your friendly engraved kitsch kiosk
associate engrave the numbers, tracing the letters with his
pantograph...

just a thought

nate

It's tough to stamp the numbers by hand and get them to look right.  Of
course, Studebaker and everyone else used a press-type machine to do this.
To get the numbers aligned and perpendicular to the tag surface, you may
need a holder for the multiple number markers.  The problem with this is
that the force required to get an indentation goes up as the number of stamp
dies increases.

Check this site for Columbia Marking Tools:
http://www.columbiamt.com/default.htm
They have number stamps and holders.  Look at the page on Marking 101.  It
has a table that shows how much force is required for various number sizes.
As their data is only for numbers up to 1/4 inch, I did a few calculations
to see what it takes for 3/8 numbers in soft brass, probably close to an
aluminum plate.  The 1/4" numbers take 3150 lbs, but a 3/8" number may need
5700 pounds and a 1/2" number about 8700 pounds.  [approximate equation is
FORCE(pounds) = 23807 x (height^1.456) ]  The force goes up faster than just
the character height because each character also gets wider and the stroke
width is wider.    It will also depend on the style of type that is used.

The Columbia chart shows that an average machinist with a 1-1/2 lb hammer
can strike with about 3 tons force.  However, in order to transfer the force
from the hammer to the stamp to the plate, the plate has to be backed up
with a strong, heavy steel block.  Laying the plate on a 2x4 or a workbench
top won't do it - too much bounce and give.  A brass hammer helps.  If you
try to do 6-8 digits at once, you had better have a very big hammer and
really heavy block!  If you are stamping the numbers into mild steel, you'll
need twice as much force.  If you hit it too hard, the number die will just
cut all the way through.

I started looking at this when I was going to make a new body serial number
plate for the firewall of my M5 and for the chassis numbers.  The numbers on
the body tag are tall, fat, and indented in reverse from the back side of
the plate.  I gave it up!

Somebody out there must have some old machines that can do the body tags.
It's more likely that you can find some company to re-do the serial numbers
stamped from the front side.