In this:
http://cedarcreekas.org/TechTopics/1...rn_Signals.pdf
"
Coil: you'll need to get a 12v coil with internal resistor. Again, available from the A vendors, although
I got a suitable one at the local parts house. Showed them the 6v coil and said “Match this size.”. They did. Turned out it was an Airtex coil 5C1019. A little sleuthing on the 'net revealed that it was used on several foreign cars, 1974 Volkswagen and 1975 MGB and perhaps others as well. This is a 12V coil with internal resistor, and it has worked very well for the past 2+ years I have been running it.
When I first made the coil change, I did not have Les Andrews' books. His recommendation is a UF-3
coil with internal resistor. (You really need to read Andrews' book. I did and it has helped immensely.)"