Mallory Ignition Issue

[ACMamba]

My Mallory ignition system in a 351 balanced Windsor has been giving
problems.

It will run-then will leave me stranded nearby with a dead Mallory distributor module-either the 6100 E-spark or the 605 version. (3 iced modules so far)
The system was originally equipped with a Hy-Fire Mallory box, but that has been disconnected earler in this car's history. It has a Promaster coil with vaccum advance Mallory distributor.

These are the symptoms-now looking for the cause. The alternator also had
a diode that went bad recently-but that has been fixed. Againower surge or spike through the system?

The ballast resistor is set at.3 OHMs to correspond to the setting needed for the mallory module. So far no other issues. Accel module in the distributor now.

Disconnected the older Promaster Mallory coil-I fitted an extra Pertronix coil and it produces almost 13.7 V while at idle-as
the car is running-but not leaving the garage/.driveway until I have this issue found and fixed.
Resistor wiring is in some cases used in the circuit between ignition switch and coil. See no evidence of this-EXCEPT-a 12 V battery strength wire coming fom the solenoid to a Hella relay/v regulator very close to the coil.
This is protected by a 35W fuse in line. Since its Hella and-a relay type
box-it very well may be a light switch. Between the unknowns and possible short to ground-in the system-
I am now going thru looking for wires rubbing against frame or loose wiring/straps anywhere in the igntion or car anywhere.

Would appreciate any ideas on this frustrating problem.

Thanks in advance...::