Suspect Rear End Stamping

[67L78conv]

Looks like the rest of the tube is pitted and that spot is smoothed out. There are lines there that could be a file or could be from something like a grinder with a heavy wire brush on it. If it was the latter the edges of the stamping should be rounded in the direction of the brush was spinning.

In short filed and stamped, I am not an expert on Nova rear stamps but that is my .02