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Old 02-14-2018, 11:08 PM   #1
ron350
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J-Studs circuit??

Just wondered what the J-studs are for and if mine look corect?
This picture is of my 75 –C10 that was ordered with only AM radio and heater and a 350 two-barrel motor.
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Stock 75 C10 step side.
350 2 BBL, 350 trans. 150K miles.
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Old 02-14-2018, 11:28 PM   #2
hatzie
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Re: J-Studs circuit??

Looks like the J-Block is setup for the 1975 I6 engine bay.
All the wires are on one stud.
The Black/White ammeter wire has an inline Bussman HFB style molded glass fuse holder. That wire is terminated in the same ring terminal as the power feed from the starter BAT wire.
The alternator and several other wires are spliced to the other RED wire upline from the J-Studs.

Download the 75 wiring diagrams from the manuals thread in my signature.
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


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Old 02-14-2018, 11:49 PM   #3
ron350
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Re: J-Studs circuit??

Thanks Hatzie.

I see that the right hand stud is smaller than the left stud. It also looks like the small black with white stripe wire is crimped in the ring terminal with the larger red wire. So it looks like there are only 2 ring terminals bolted to the large left stud is that correct?

The truck had aftermarket air installed a few years after it was new and I don’t know if they changed any of the wires.
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Stock 75 C10 step side.
350 2 BBL, 350 trans. 150K miles.
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Old 02-15-2018, 08:41 AM   #4
hatzie
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Re: J-Studs circuit??

The original GM J-Studs are two different sizes... 1/4" & #10.
The wiring diagrams show the two wires I described in one ring terminal for the Inline 6 engine compartment and only the #10 stud in use.
It's a common thing to change from the 250CID or 292CID Inline-6 to a V8.
Is the third digit of your VIN Q or T?
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.
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Old 02-15-2018, 12:44 PM   #5
kwmech
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Re: J-Studs circuit??

I use those as a Junction box when moving the starter wires to a Ford solenoid set-up. BUT I jump the 2 terminals with a fusible link after eliminating the factory wiring end you see there
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Old 02-15-2018, 01:45 PM   #6
ron350
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Re: J-Studs circuit??

OK the vin number is CCV145A######

I forgot the truck was also ordered with power brakes and power steering. Instead of a fan clutch it came with a 2-1/2 inch aluminum spacer and a solid fan. The truck sounded like a small airplane going down the road.
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Stock 75 C10 step side.
350 2 BBL, 350 trans. 150K miles.
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Old 02-15-2018, 01:51 PM   #7
hatzie
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Re: J-Studs circuit??

Interesting. V is a 350-2 according to the parts books.
Prolly it should read base model... not just the I6 but also any other base model with an optional engine.
It's a valid factory wiring arrangement. If it works why worry about it?
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.
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Old 02-15-2018, 02:24 PM   #8
ron350
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Re: J-Studs circuit??

Thanks Hatzie that’s what I wanted to know.
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Stock 75 C10 step side.
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