I was visiting with several members of my Model A club today and one of them was showing the 1/2" breaker bar that he ground down to fit the rear end plug in his 1931 coupe. One of the other guys mentioned that 7/16" bar stock fits the same place. I'm thinking that the next time I'm at the steel supplier's I'll snag a foot or so of 7/16" bar stock and bend it (with heat) like an Allen wrench and throw it in the trunk. I don't remember now how I removed that plug but I've checked the rear lube (1930 sedan) and added some a while back. Alternatively, I might cut up a socket and weld a short piece of the 7/16" to it so it can be used.
fwiw, the previous owner of my "A" cut down a 1 3/8" socket and welded a flat bar to it to use on the crankshaft nut to turn the engine over while timing the engine (to find the "dimple" in the timing gear).
I bet that if everyone on here showed his/her homemade or modified tools for use on Model A's I would be astounded.
Is there a "homemade tools" thread on here somewhere that I haven't found?