HEI... here we go...

I should send you a gold Pentastar to stick on that big glaring "GM"! Nice work.

Here is the GM 5 pin HEI hack: "5 pin HEI module out of an '80 Oldsmobile Toronado w/ 307 or 350 engine, works just like a "regular" 4 pin HEI module, but ground the 5th pin and it will retard crank timing 5 degrees" Another states 5 pin HEI "Used on early non-efi HEI vehicles for detonation control such as 1980 Pontiac TransAm Turbo (301 olds), retards BY 10 deg when 5th pin is grounded" eg. Standard Motor Products #LX-330 (?)