Murray said

Thanks for the help. Just got done studying '68 wiring diagram. At least for '68, there are two grey wires in the car. The grey wire going through the bulkhead connecter is the feed for the oil pressure sender on the block. It is grey with no tracer. Factory manual shows tach wiring as an independent add-on loom, added at the fuse block. The grey wire, no tracer, does feed through the firewall in it's own independent location, on its way to the coil. Great discussion, just need picture of exact location of that exit location.Thanks.

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