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Curt 55311 Custom Wiring Harness for GMC K15/K25/K35 1973-1978

Brand: Curt
Part Number: 55311
Product Type: Wiring Harness
Vehicle Fitment: GMC K15/K25/K35 1973-1978
Condition: New
Shipping: Flat Rate Shipping
Was: $71.64
Sale: $50.15
Save: 30%
Save: $21.49



Curt custom wiring provides everything you need to connect your vehicle's electrical system to a trailer. With plug-and-play connectors, a custom wiring harness easily integrates with your vehicle taillights to provide a standard trailer wiring connector, typically in the form of a 4-way flat. This custom wiring harness features a vehicle-specific design to perfectly fit certain years of the gmc k15/k25/k35 (to verify vehicle compatibility, see the Curt application guide). It uses OEM-compatible connectors to "T" into the vehicle's taillight assembly and provides a standard 4-way flat output to power the taillights, brake lights and turn signals on your trailer.


  • Plugs into existing OEM vehicle socket to provide a 4-way flat socket
  • Simple plug-and-play design eliminates the need for cutting or splicing
  • 4-way flat output connects tail lights, brake lights and turn signals
  • Dust cover included to keep connector clean when not in use
  • Backed by a limited one-year warranty


  • Electrical System Type: 2 Wire
  • T-Connector Location: S1, S2
  • Output Type: 4-Way Flat
  • Installation Difficulty: Easy

Vehicle Fitment 

Year Make Model
1973-1978 GMC K15
1973-1978 GMC K25
1973-1978 GMC K35

Technical Files 

Installation Instructions




Shipping Information

  • Item Requires Shipping
  • 1.0 lbs.
  • W1.0000” x H1.0000” x L1.0000”
  • $14.95
  • Flat Rate Shipping

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