Electronic ignition problems/tach not working

[1972 911 T]

Does anybody know the specifics about the factory Bosch ignition module for a 72T? Specifics meaning: resistance / capacitance readings between certain pins, voltage at the coil while the car is running (I am getting 0).

The primary ignition wiring seems to match the schematic from the factory manual, except one minor detail. The distributor picture on the schematic shows the moveable (insulated from ground) contact of the points going to ground and pin D!?!?! I currently have the oposite, which I believe to be correct - pin D and ground going to the dist. body and the insulated terminal going to the module (pin A?) and the tach wire.

The car runs pretty well as is, but no tach. I have checked everything I can think of - 12V between the rd/bk wire and ground (brn. wire), voltage at the bk/pr wire to ground (~7V pulsating), frequency in Hz between bk/pr and ground (40Hz at idle), different tach from 71 911, Perma Tune module, hook tach up backwards (bk/pr to "-" terminal, rd to "+" terminal, brn to "1" terminal). The tach will work in this configuration, but it doesn't seem accurate, and the engine dies when the high beam indicator light is pushed in to the tach housing indicating that I'm grounding the primary circuit through the indicator light.

Alex