as MVWCNEWS stated, that looks like Walden's style W
if you check our Walden's number 6018 9/16" speed wrench, in 1928 they listed it for;
Ford Model A & T and they listed some of the uses for it.
ball and socket bolt nut
intake and exhaust manifold
cylinder to lower base
fan bracket bolt
magnet screw caps
transmission cover bolt and nut
transmission drive plate screws
timing gear cover
and other applications ?????
NOTE; in 1917, they made the same wrench with a wood knob handle, 9/16" and they listed it as designed for
use on transmission cover nut and engine base nut. Walden No. BS18
I have both, the BS18 & 6018
they may have made the wrench special for garage repairmen to work on that rear end. Walden was a great leader in manufacturing
wrenches for auto repair and they concentrated heavy on Mr. Henry Ford's tin lizzy.
just my 2 cents worth, Frank