Alan,

Here is a M-H plough (plow) wrench which I was going to post last year on your excellent wrench thread on the old website, unfortuneatley this was the one which never made it so hope it works now!

It came new in 1934 with my dad's new M-H No23 plough and 12-20 tractor from local agents Ward and Co of Horncastle Lincolnshire. The part numbers are not readable but definately starts with PE and it fits the large nut which holds the lift mechanism hub into the left steel wheel, which is the large nut behind the hub cap on the land wheel.
I am sure you will have found and listed this one.

Malcolm.