To me that looks like very common build-up from debris that settled in the tub. I would not worry about it. It may need a scrubbing to get off, but unless the porcelain finish is compromised, the rust should not be permanent.
That looks very much like a tall centerpost (there were three centerpost heights in 18lb. machines over the years). That is the second generation agitator, which was "shrunken" to lessen wear on the gearcase.
I'd grab it!