[Walt Fricke]

If Mr. Rice's '78 SC had an oxygen sensor, it had an '80 or later engine transplanted into it because the '78s didn't have O2 sensors. However, that is a strange plug. I've not seen one like it elsewhere, and certainly not elsewhere in a 911. It looks like the wire from the plug forward in the wire loom to the little computer under the passenger seat (this is a separate loom from the main loom) is or may be coaxial. And it gets its ground, I think, from where it connects to the computer. I think that is all that is required for the outer braid to do its shielding job.

The SC oxygen sensor is a one wire sensor, and that one wire is all there is from the sensor to the plug in question. So the advice to just use some other kind of connector is good. A BNC connector is overkill, because the shielding stops at the connector.

Walt Fricke