Jack,

Here are some more shreds and shards of information. According to the 1959
Allied catalogue there were 5 different "LS3" coils sold with differing
catalogue numbers. Each is advertised with a paper-based phenolic core and
the slug for the LS3 is described as "a larger slug" (as opposed, I suppose
to a smaller iron slug on the other coils in their line). No L value is
mentioned in the 1959 or any other copies of the Allied catalogue that I
have. Each of the five LS3s is described with a coil that is 1 1/8' x
3/8-inch diameter. They produced the following LS3 coils: 1 MC, 5 MC, 10 MC,
30 MC and 60 MC. If I knew the wire size I might be able to come closer to
deducing an L value.
Good luck.

73 es ZUT Vern W9STB