1974 GMC Mason electrical

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Hew Klaus

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Joined
Mar 28, 2025
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Location
London, Ohio
First Name
Matt
Truck Year
1974
Truck Model
K3500
Engine Size
350
Hello everyone. I purchased a 1974 GMC Mason last year. Very simple design. 350 4bbl 4 speed manual. Using it for a small business I am trying to start. Stepson is the labor part of the business and mainly drives it. While driving it around some wires on the left side of the firewall were damaged. I have a strong electrical background but without a wiring diagram I can't do much to reconnect them. Can anyone give me direction for sourcing a wiring diagram?
 

Mr Clean

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Location
North East Texas
First Name
Shawn
Truck Year
1982 & 1985
Truck Model
K10 Extra Cab w/ Proper SWB, & 85 K5 Blazer
Engine Size
454 BBC, & 383 Stroker
:welcome:
 

Sad Sack

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Location
Nebraska
First Name
Goober
Truck Year
1985
Truck Model
C15
Engine Size
305
Also, really nice, affordable and color coded:

 

WFO

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Location
Texas Panhandle
First Name
Dan
Truck Year
1986
Truck Model
K20
Engine Size
350
Welcome from the Texas Panhandle.
 

86 C10 Shortbed

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Location
Ohio
First Name
Mark
Truck Year
1986
Truck Model
C10
Engine Size
5.3L
Welcome from Reynoldsburg, OH
 
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