I just got my 1938 John deere Model D in March and have been researching the lubricating schedule for it. The "Transmission Filler Plug" on my 38 and the drain plugs are square with cuts in each corner. The plug looks to take a 3/4" drive to open and close it, but a 3/4" drive is just barly too big for it.
Is there a tool that I need to find that was used back when it was made, or is there one that I can use in it"s place that I can find in a hardware store? The cuts in the corner of the square make me think the device was more like a key of some kind?