I can't find a similar level on eBay or anywhere else, and certainly not
to
a No. 13.

Anyone know anything about this level, age, etc., or where I can learn
about
it?

Per Walter's book:

13 "Victor" Carpenter's Adjustable Plumb & Level
1911 to 1938

Sweetheart logo would be 1920 to 1935 approx.

It would have had a center bubble.

probably worth less than $5.00

scott

$5-??? Ouch! I have the same level here, it's not much chop for fine
cabinetry but for fencing and noggin-work in house framing it's ideal; I
still use it.

Heck, 'tis even adjustable, which is more than can be said for the
cheap'n'nasty plastic & alum. Stanley I bought recently at 10x that $5- and
relegated to the back shed with other "junk" tools...

- Andy