[Heathkit] Can't ID older desk mic

[Dave Haney]

I have an older Heathkit  cream-colored desk mic that has no model 
number info on the bottom plate. The plate says "Low & High Impedance" 
and there is a detailed wiring schematic.

Can anyone tell me what model this mic might be ?

Mni tnx.

73
Dave Haney
W3SJ