Help identifying dash wiring harness plugs

[351mach1]

Please help identify these connections. This is every plug I could find under my dash. I will update my OP with answers as others may find this a useful reference. If this already exists, I'd love to see it. It was suggested that this is a 72 harness with automatic transmission and A/C but the car is originally a 71 with manual and A/C. If you know the designation of the plug, that's even better (like c-21 or whatever it shows on the diagram).

I am also looking to figure out how to confirm if my car originally came with a tach and if this harness is for a tach

1: Rear Lighting (please let me know if you know specifically)
2: Rear Lighting
3: Trunk courtesy lighting
4: ?? (located at main wiring harness firewall pass through)
5: C-136 Headlight/Dimmer Switch
6: Optional under dash courtesy light
7: Windshield Wipers
8: Cigarette Lighter
9: C-21 (Emissions-goes to engine bay on firewall)
10: C-28 Ignition Switch
11: Turn Signals/Horn
12: 4 way flashers
13: Radio
14: Clock
15: Blower Motor
16: ? (Maybe a light)
17: [heater/AC extension plug to mate switch to blower motor]
18: Cut wires to 17
19: Center console gauges (c-114???)
20: power and output from circuit breaker to 4 way flasher
21: Turn Signal Flasher
22: optional parking brake and headlight on for convenience panel
23: RH underdash optional courtesy light
24: Seat Belt Light

 

[midlife]

Please help identify these connections. This is every plug I could find under my dash. I will update my OP with answers as other may find this a useful reference. If this already exists, I'd love to see it. This is a 72 harness with automatic transmission and A/C. If you know the designation of the plug, that's even better (like c-21 or whatever it shows on the diagram)

1: Rear Lighting (please let me know if you know specifically)
2: Rear Lighting (please let me know if you know specifically)
3: ?
4: At main wiring harness firewall pass through
5: C-136 Headlight/Dimmer Switch
6: ?
7: Windshield Wipers
8: Cigarette Lighter
9: C-21 (Emissions-goes to engine bay on firewall)
10: C-28 Ignition Switch
11: Turn Signals/Horn
12: ?
13: ?
14: ?
15: Blower Motor
16: ?
17: ?
18: ?
19: Center console gauges (c-114???)
20: ?
21: Turn Signal Flasher
22: ?
23: ?
24: Seat Belt Light
View attachment 95458View attachment 95459View attachment 95460View attachment 95461View attachment 95462View attachment 95463View attachment 95464View attachment 95465View attachment 95466View attachment 95467View attachment 95468View attachment 95469

This is for an early 1971. How do I know? Your plugs 1 and 2 were changed early on.
3. for rear trunk courtesy light option
6.for optional underdash courtesy lights
12 4 way emergency flasher plug
13. radio power and lights
14. clock plug
16. For light on console?
17. This is what I call the heater/AC extension plug to mate switch to blower motor
18. Cut wires to 17.
20. power and output from circuit breaker to 4 way flasher
22. optional parking brake and headlight on for convenience panel
23. RH underdash optional courtesy light

 

[351mach1]

Does the Marti Report tell if mine originally came with Tach? How can I verify if the harness in the vehicle is supposed to be for a tach cluster? It currently has an inoperable clock cluster in it but it wasn't even hooked up at all. It has the three gauges in center console

Here's what's confusing: The car is a 71 m code with 4 speed and A/C from California. It was converted to a later (73-74) engine and auto tranny. I have a hunch that there was a 72-73 donor car involved as a bunch of the dash is from a 72 [to my understanding] as it has the seat belt light above the glove box. I am trying to not make assumptions about anything that's in there. It has all the appropriate plugs for the auto transmission (and maybe an extra?). I think it would have been easier for them to just swap a full wiring harness from a donor than to disassemble two complete wiring harness' just to add the auto trans plugs.

 

[Sheriff41]

Yep. The instrumentation group included the tach and the oil, amp, and temp gauges.

 

[Sheriff41]

https://7173mustangs.com/images/71factbook.pdf