Searching a Subaru users group in Australia, I came across the following "fix" replacement part that they use on the "Brumby:
Here's a link to the site: http://www.peelinstruments.com.au/index.html
& here are the details of the part:
CP30 Safety Switch
This device is designed to turn off power to the Gas System when the engine stalls/turns off. The unit senses a Coil/Tacho pulse to provide power to the Gas System. Unit is capable of supplying an output of up to 12 amps. Unit is capable of picking up a faint pulse.
Wiring-
GND/NEG - Ground/Earth
GAS+POS12V – Input 12 Volt power from Gas side of switch
Lock Off+Pos Gas – Output 12V power to Gas Lock Off.
NEG COIL - Tachometric Output Pulse/ Neg. Side of Coil.
Any advice is much appreciated!~
Bratmobile