- Joined
- Aug 7, 2016
- Posts
- 9,745
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- 23,059
- Location
- Weiser Idaho
- First Name
- Perry
- Truck Year
- 1975-1979
- Truck Model
- K20-K10
- Engine Size
- 350
^^^^^^^^^^^^used to, huh?^^^^^^^^^^^^^^^ 
all time 4 wheel drive
- Thread starter 1972Camaro
- Start date
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- Joined
- May 16, 2017
- Posts
- 2,501
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- 6,709
- Location
- California
- First Name
- Mike
- Truck Year
- 1973, 2000
- Truck Model
- K10, 1500
- Engine Size
- 5.3l
I'd find all the VIN numbers and see if they match up after @buckets description of your truck. And maybe say high to the group, how you got the obtained it, and more pictures. Some history and did I say we like picture lots of them.
There is a VIN number on top of the frame just aft of the power steering pump. There is also a date and time stamp of the side rail of the frame by the passenger side gas tank that will tell you the year of the frame. That should give some more idea of what you have.
There is a VIN number on top of the frame just aft of the power steering pump. There is also a date and time stamp of the side rail of the frame by the passenger side gas tank that will tell you the year of the frame. That should give some more idea of what you have.
You must be registered for see images attach
You must be registered for see images attach
75gmck25
Full Access Member
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- Oct 13, 2016
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- 2,786
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- 3,099
- Location
- Northern Virginia
- First Name
- Bruce
- Truck Year
- 1975
- Truck Model
- K25 Camper Special TH350 NP203
- Engine Size
- 5.7
Definitely not an ‘85 truck. If they mixed and matched between years and did not notify DMV it may be difficult to get a valid title.
Older trucks had a shorter VIN, it was not displayed in a window in the dash bezel, and they usually can’t be easily verified as valid with newer online VIN checking tools. An ‘85 would have the longer VIN (now standard) and I think it’s visible in a window in the dash pad.
Older trucks had a shorter VIN, it was not displayed in a window in the dash bezel, and they usually can’t be easily verified as valid with newer online VIN checking tools. An ‘85 would have the longer VIN (now standard) and I think it’s visible in a window in the dash pad.
goldpack
Full Access Member
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- Jul 8, 2025
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- 615
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- 1,199
- Location
- Adirondacks, NY
- First Name
- Donnie
- Truck Year
- 1986
- Truck Model
- GMC C2500 Camper Spec.
- Engine Size
- 350 with 350 3 speed
so...a 1970s gmc full time 4wd sucks balls that bad ? = "from the wheels that grip, to the wheel that slips"?
- Joined
- Aug 7, 2016
- Posts
- 9,745
- Reaction score
- 23,059
- Location
- Weiser Idaho
- First Name
- Perry
- Truck Year
- 1975-1979
- Truck Model
- K20-K10
- Engine Size
- 350
Yep if it ain't in lock or doesn't have a limited slip.....it's a one wheel drive
75gmck25
Full Access Member
- Joined
- Oct 13, 2016
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- Location
- Northern Virginia
- First Name
- Bruce
- Truck Year
- 1975
- Truck Model
- K25 Camper Special TH350 NP203
- Engine Size
- 5.7
I have a 14 bolt FF with G80 locking differential, and I know how to shift my truck to 4 Loc. No problem with driving in mud and snow. You just have to understand how the drivetrain works.
77Dmax
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- Nov 10, 2024
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- 694
- Location
- vt
- First Name
- Joe
- Truck Year
- 1977
- Truck Model
- c20
- Engine Size
- 6.6
I had a 77 blazer for awhile. It was kinda unpredictable in the snow. Sometimes the front would spin when i thought the rear would or vice versa. It was fine when locked. It also got the worst fuel mileage...
Safetyguy
Junior Member
- Joined
- Nov 10, 2021
- Posts
- 9
- Reaction score
- 4
- Location
- Central Coast, CA
- First Name
- Greg
- Truck Year
- 1977
- Truck Model
- K20 Scottsdale Camper Special
- Engine Size
- 400
Bought my '77 K20 new. One of the first things I di was put in a Doug Nash (4/2?) part time conversion kit. It replaced a shaft and some gear in the transfer case and came with Warn hubs. It was so much better driving on paved roads and in town without the front wheels engaged. 4WD, just lock in the Warn hubs and pull into 4WD. Easy peazy.
I don't think they have been available for quite some time; maybe others are still made?
I don't think they have been available for quite some time; maybe others are still made?
- Joined
- Sep 10, 2023
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- 981
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- Location
- KY
- First Name
- Bill
- Truck Year
- 1978
- Truck Model
- K20
- Engine Size
- 400
This Forum gave me the info I needed when I began the rebuild of my '78 equipped with the 203... I had no idea about that era of TCs, and how they operated.
I replaced it with a 208 and added TruTrac diffs
I replaced it with a 208 and added TruTrac diffs
