Wiring harness compatability - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1986c10 · 06-09-2015, 10:38 PM

Hi, quick and probably stupid question. I have a 1976 Gmc K20 that has the tail light wiring at the lights that comes together under the tailgate area. It is missing the wiring that goes to the cab. Am I missing just one harness that will plug into the cab or possibly a couple? Also what year harness(s) would fit? Ive found a couple late 80's c10's being parted out locally and was wondering if I could snag the parts off them. Thanks!

1986c10 · 06-11-2015, 08:25 PM

Anyone have an idea?

silverbear · 06-11-2015, 08:51 PM

It should be one harness from the firewall bulkhead connector all the way back to the T under your tailgate. One difference i know of is the connector in the back changes a few times over the years. Some are round, some square and some flat.

1986c10 · 06-11-2015, 09:03 PM

Thank you for the information! I guess I could cut the connectors off and splice the body harness to the tail light harness.

mtnsackett · 06-11-2015, 09:23 PM

Are you looking for the Intermediate or fire wall to rear frame connector section? if so 73 to 78 should fit If i Remember correctly you can get it new from classic ind for around $100

1986c10 · 06-11-2015, 10:39 PM

Yes thats what I need, whatever comes from the cab to the harness by the tailgate with the bulb connectors etc. I looked on classic industries and could only find the harness for the tail lights themselves, not the chassis harness wiring unfortunately. I figured this would be a common part but ive googled alot and cant find anything.

*gmachinz* · 06-11-2015, 10:48 PM

I'll have NEW rear body harnesses available soon but they aren't ready yet. Same with the tank harnesses...single and dual. If you haven't found anything in a couple weeks PM me as I should have my first batches ready.

**hatzie** · 06-12-2015, 10:08 AM

Quote:

Originally Posted by silverbear

It should be one harness from the firewall bulkhead connector all the way back to the T under your tailgate. One difference i know of is the connector in the back changes a few times over the years. Some are round, some square and some flat.

It's just 4 wires that run from Packard 56 terminals at the bulkhead plug to the disconnect on the frame.

The squares have 2 different lamp end disconnects
1973-1984 will have a round molded connector at the Lamp to Body/Frame harness disconnect.
1985-1991 will have a square 4 position Weatherpack connector at the lamp end.
The flat connectors are on some of the 88-01 T400 chassis.

The harness length will vary depending on the distance from the cab to the end of the bed. Crew vs standard cab and 6' vs 8' bed.

If the harness is missing I would lean toward the 85-91 Weatherpack setup because I have the tooling to fab it.

Quote:

Originally Posted by gmachinz

I'll have NEW rear body harnesses available soon but they aren't ready yet. Same with the tank harnesses...single and dual. If you haven't found anything in a couple weeks PM me as I should have my first batches ready.

The molds for those earlier connectors are not cheap to make. It's a risk but everything is.

06-09-2015, 10:38 PM	#1
1986c10 Registered User Join Date: Apr 2010 Location: Vicksburg, Mi Posts: 323	Wiring harness compatability Hi, quick and probably stupid question. I have a 1976 Gmc K20 that has the tail light wiring at the lights that comes together under the tailgate area. It is missing the wiring that goes to the cab. Am I missing just one harness that will plug into the cab or possibly a couple? Also what year harness(s) would fit? Ive found a couple late 80's c10's being parted out locally and was wondering if I could snag the parts off them. Thanks! __________________ 1979 C10 - swb, mild 327, restoration project 1979 Mustang - Turbo 5.3 / 4l80e 1976 K20 - Mild 396, 6" lift, 35's - sold 1986 C10 - lwb vortec 355- sold 1982 C10 - swb project- sold

06-11-2015, 08:25 PM	#2
1986c10 Registered User Join Date: Apr 2010 Location: Vicksburg, Mi Posts: 323	Re: Wiring harness compatability Anyone have an idea? __________________ 1979 C10 - swb, mild 327, restoration project 1979 Mustang - Turbo 5.3 / 4l80e 1976 K20 - Mild 396, 6" lift, 35's - sold 1986 C10 - lwb vortec 355- sold 1982 C10 - swb project- sold

06-11-2015, 08:51 PM	#3
silverbear Registered User Join Date: Feb 2014 Location: Glen St. Mary, Florida Posts: 304	Re: Wiring harness compatability It should be one harness from the firewall bulkhead connector all the way back to the T under your tailgate. One difference i know of is the connector in the back changes a few times over the years. Some are round, some square and some flat. __________________ 86 Chevrolet K10 350/SM465 Frankie SOLD 1995 GMC Yukon GT SOLD 1996 GMC Yukon GT 2010 Suburban 1500 4x4 5.3l/6L80e. Sold 2016 Silverado 2500HD Crew Cab 4x4 6.0l/6L80e

06-11-2015, 09:03 PM	#4
1986c10 Registered User Join Date: Apr 2010 Location: Vicksburg, Mi Posts: 323	Re: Wiring harness compatability Thank you for the information! I guess I could cut the connectors off and splice the body harness to the tail light harness. __________________ 1979 C10 - swb, mild 327, restoration project 1979 Mustang - Turbo 5.3 / 4l80e 1976 K20 - Mild 396, 6" lift, 35's - sold 1986 C10 - lwb vortec 355- sold 1982 C10 - swb project- sold

06-11-2015, 09:23 PM	#5
mtnsackett Registered User Join Date: Jun 2010 Location: Centerville, MN Posts: 81	Re: Wiring harness compatability Are you looking for the Intermediate or fire wall to rear frame connector section? if so 73 to 78 should fit If i Remember correctly you can get it new from classic ind for around $100 __________________ "Not all those who wander are lost." A.R.R. Tolkien... Some of us are exploring to see what is out there in this world!

06-11-2015, 10:39 PM	#6
1986c10 Registered User Join Date: Apr 2010 Location: Vicksburg, Mi Posts: 323	Re: Wiring harness compatability Yes thats what I need, whatever comes from the cab to the harness by the tailgate with the bulb connectors etc. I looked on classic industries and could only find the harness for the tail lights themselves, not the chassis harness wiring unfortunately. I figured this would be a common part but ive googled alot and cant find anything. __________________ 1979 C10 - swb, mild 327, restoration project 1979 Mustang - Turbo 5.3 / 4l80e 1976 K20 - Mild 396, 6" lift, 35's - sold 1986 C10 - lwb vortec 355- sold 1982 C10 - swb project- sold

06-11-2015, 10:48 PM	#7
gmachinz Account Suspended Join Date: Jun 2011 Location: Des Moines, IA. Posts: 4,143	Re: Wiring harness compatability I'll have NEW rear body harnesses available soon but they aren't ready yet. Same with the tank harnesses...single and dual. If you haven't found anything in a couple weeks PM me as I should have my first batches ready.



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