L78 Holley Rebuild...

[Mr70]

"I also noticed in the pictures that your green colored TCS plug wire that mounts to the switch on the passenger side head has a brown colored plug head on it. I was told that the brown colored plug heads started to surface on the mid to late seventy production cars and the earlier ones used a grey colored plug which is what the repro ones are colored. I had to get a repro one for my car because that portion of the wire was hacked off years ago by the previous owner. Luckily I still had the wiring and black colored plug head that plugs into the TCS solenoid on the intake. I found this coiled up in the wiring gutter..."

I've only seen either the Black or the Brown TCS plug installed here originally on the 1970 Big Blocks so far...Cars like Bill B.,Dennis C.,Dave G.,Tony P.,& Dean R. survivor LS-6's to name a few.
I've only encountered the Grey on Small Blocks & have factory photos showing Grey on them too,but still not certian it was exclusive to just the SB.