I have really gone around in circles on this one. I am currently running a 1955 235 with a 1953 distributor converted to 12 volt negative ground. From a previous thread I figured I needed a 1157P12 unit. When it showed up it said positive ground on the box so I knew that wasn’t going to work. Turns out 1157 is for the older distributor with a 12 volt conversion. 1157N6 is what’s required for those not converted. 1158 is supposed to be for 1955-1962 12 volt distributors. I returned the positive ground unit to Pertronix and they said they would exchange it for a negative ground one. It arrived in the mail and it’s the exact same one as I returned so now I have to do it again. Does anyone know the difference between the 1157 and 1158 as in the future I will be dropping in a 1956 261 and would like to use the same unit. Hopefully it’s just a small difference in the mounting plate that I can modify. Since I have to return it again I am wondering if I should just get the 1158. Anybody familiar with this?

Thanks,

Curt B.

1952 1300 Canadian 1/2 ton restomod
You Tube