While refurbishing 69 and 70 wiring harnesses, I've seen at least four variants of 1970 heater box wiring. All four variants are all electrically equivalent, but have different connectors (some with extensions) and locations for where these wires break out of the main harness. I am at a loss to understand why these versions are so different, but that may be because I am unfamiliar with the 70 heater boxes, of which there may be variations in design and/or location. While the advantage I have is seeing well over 200 harnesses, the drawback is that I don't know the factories or VIN numbers associated with them. Very few harnesses have stickers still attached to help decipher if there was a sequence in time of designs.
The first style is what I call "standard", and covers roughly 75% of all 70's and 95+% of all 69's. This style has the three prong spade connector (red, blue, black/yellow) that plugs into the heater box breaking out of the harness near the passenger side door jamb switch.
"Standard" style:
What I call Style A has the break-out on the portion of the harness going towards the firewall plug, and the plug is a three-prong flat bullet plug. I believe there is an extension that converts this bullet plug to the standard spade connector in "standard".
Style A:
What I call Style B has the same position for the wire breakout of the main harness, but has a longer length and ends up in the "standard" spade plug.
Style B:
I have one picture of this style used in 1969. Almost all 1969's have the "standard" style, which may suggest late 69 and early 70's may have started as Style B.
1969 Style B:
Style C is the rarer of all, and is a combination of "standard" and Style A in that there are two heater box connectors: one breaking out near the passenger side door jamb and the second on the firewall portion of the harness. The heater switch connector itself has doubled up wires.
Style C pictures:
Here's what I can tell so far about these variants. "Standard" style has stickers that show the parts end in at least -B9 and -CH; Style A has a B0, and the 1969 Style B has a -BC suffix. I can't correlate the four variants to the presence of AC, tachometer, or Mach1 configuration. With AC, tach, and Mach1 configurations, there are at least 8 basic configurations for 1970 harnesses (standard or tach dash, with or without A/C, Mach1 or not).
What can y'all tell me about 1970 heater boxes? Were they different throughout the year? Different locations?
