I was up at my friend's workshop today and he had an old P50 sitting outside his door that some guy had dropped off for him, sounded like to keep. In about the same condition, by the looks of it, though it has a full-wrap handle.
Anyway on a different topic, I got talking to him about using FOPs for rakers etc. and he showed me his "favorite depth gauge ever", one which I'd never seen before:
He has two of them - this one is his original which is apparently worn out; I guess the edges of the gap in which the raker depth plate itself sits have gradually gotten eaten away by errant file strokes, so it's no longer very accurate.
He apparently got these from the Pioneer dealer in town here ages ago, said this one in the pics is the first from ca. 1961, thinks he got it the same time he bought his first 750. Anyway he'd love to get one or two more, and frankly after seeing it I wouldn't mind having one too. He can't find anyone with them though, so I told him I'd take some pics and ask around here. Jerry, Brendon, Lawrence, you guys have any ideas or literature on them? At least there's a part number to work with.