OK. Get a 2-inch speaker and Radio Shed's 1KCT-8 transformer. Wedge the speaker into the Shure case; cardboard and foam may be useful. Wire the speaker to the 2-leg side of the transformer. On the other side, take the center pin and an end pin. (Bend-over the unused endpin so it won't touch anything.) These go to the two signal pins on an XLR. The mike case goes to the XLR ground pin.
It isn't "same as", not by a long shot. But it is lo-fi with a strong 4KC peak and narrow beamwidth in treble, just like the Shure used to be. And it interfaces just like an SM58, plain old 250 ohm dynamic mike. Goesinta any "normal" (modern) XLR mike input.
