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#1 |
Registered User
Join Date: Mar 2005
Location: Just outside Durham, NC
Posts: 894
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I seem to remember reading a while back that the 3/4 ton trucks have boxed frames, where as the 1/2 ton trucks have the c channel frames, is this correct? and I know that the two variants run different axles and springs, but can anyone give me more specifics than that?
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#2 |
'68 C-20 396 CST CC
![]() Join Date: Mar 2005
Location: Spokane, WA
Posts: 454
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Larger brakes-- pads, wheel cylinders, and brake springs (not sure about the master cylinder--the front spindles are different as well...larger hubs (8-lugs)...
Along with larger spindles and axles (Dana 60,70 and Eaton rear ends) The wheel bearings are larger on those components as well to handle more load. I know my 3/4 ton has a heavy-duty stabilizer bar and a rear end stabilizing link that isn't on my 1/2 ton. I'm not sure about the frame differences though...
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68 C-20 396/TH400 CST Custom Camper NOW W/DISC BRAKES ![]() 01 Jetta Turbo Daily Driver ![]() 84 Yamaha Virago 700 - Alaska to Florida Via Maine & Mexico ![]() |
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#3 |
Registered User
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Location: NM
Posts: 705
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I've seen several trucks that have been switched from one to the other, so if there are differences they must still be compatable with the other's running gear.
Nik |
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#4 |
Senior Member
Join Date: May 2001
Location: West Central Minnesota
Posts: 568
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The frames are basically the same, 3/4 tons aren't boxed.
Bob
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V-6....only GMC Trucks have it! 62 GMC W5000 NAPCO-V6 65 GMC 2500 NAPCO Panel-V6 66 GMC 1000-V6 66 GMC 1500-V6 67 GMC K1500-SBC (originally a KM-V6) 68 GMC C1500-V6 68 GMC C1500-V6 68 GMC Suburban C2500 70 Chevy K20-SBC 71 Chevy C30 Longhorn-SBC 72 GMC Suburban C1500-BBC 72 Chevy C10-SBC 72 GMC C5500-ToroFlow Diesel |
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#5 |
Senior Member
![]() ![]() Join Date: Jan 2005
Location: CA
Posts: 5,527
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I believe the 3/4 Ton Chassis have a couple angled braces between the side rails and the crossmember that the driveshaft passes through. There was a picture in a thread several months ago.
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#6 | |
'68 C-20 396 CST CC
![]() Join Date: Mar 2005
Location: Spokane, WA
Posts: 454
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Quote:
I keep hearing different things about the frames...my 1/2 ton frame doesn't look any different than my 3/4 (both '68s). One guy on this board once wrote that they used thicker steel in the 3/4 but I can't tell a difference. Anyone ever read anything "official" on this in any GM publication?
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68 C-20 396/TH400 CST Custom Camper NOW W/DISC BRAKES ![]() 01 Jetta Turbo Daily Driver ![]() 84 Yamaha Virago 700 - Alaska to Florida Via Maine & Mexico ![]() |
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#7 |
December 21, 2012
Join Date: Apr 2000
Location: Black Eagle, Montana
Posts: 1,634
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My 3/4 ton frame isnt any different than by 1/2 ton frame. Front end parts and the rear end are heavy duty compared to 1/2 ton and thats about it.
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"!Ama Sua, Ama Kjella, Ama Lllulla!" |
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#8 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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The 3/4 ton has some bracing that the 1/2 ton doesn't. That is it as far as frames.
The trailing arms on a 3/4 ton are stronger. |
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#9 |
huh ???
Join Date: Nov 2002
Location: Fredericksburg,Va.
Posts: 3,369
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I know the front brakes on the front of my 72 C/20 uses the same D52 brake pads as my 86 K/10...
Chuck
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90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!" |
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#10 |
Registered User
Join Date: Apr 2003
Location: NB
Posts: 3,367
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same frame stronger "gusets" on the 3/4 ton.
rear end is bigger and so is the brakes
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1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD |
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#11 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
Posts: 12,684
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The GM restoration packet indicates the C10, C20, K10 and K20 frames all use 39,000-lb-test steel. The C10 frame section modulus is 2.98 while a K10 frame section modulus is 2.70.
The C20 frame section modulus is 3.71. The K20 frame section modulus is 3.48. I found this definition of section modulus: Section Modulus - A measurement that is calculated based on the shape of the cross section of the rail (what the frame rail looks like when it’s viewed from the end). A tall rail made of thick material will have a higher section modulus than a short rail made of thinner material. Additionally, adding an insert will increase the section modulus of the rail. Section modulus has a direct effect on the stiffness of a rail.
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#12 |
Senior Member
Join Date: May 2001
Location: West Central Minnesota
Posts: 568
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Any mention of the section modulus for a C30?
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V-6....only GMC Trucks have it! 62 GMC W5000 NAPCO-V6 65 GMC 2500 NAPCO Panel-V6 66 GMC 1000-V6 66 GMC 1500-V6 67 GMC K1500-SBC (originally a KM-V6) 68 GMC C1500-V6 68 GMC C1500-V6 68 GMC Suburban C2500 70 Chevy K20-SBC 71 Chevy C30 Longhorn-SBC 72 GMC Suburban C1500-BBC 72 Chevy C10-SBC 72 GMC C5500-ToroFlow Diesel |
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#13 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
Posts: 12,684
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My restoration pack unfortunately only address the 1/2 ton and 3/4 tons.
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#14 |
Senior Member
Join Date: May 2001
Location: West Central Minnesota
Posts: 568
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Will they do a restoration pack for a C30?
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V-6....only GMC Trucks have it! 62 GMC W5000 NAPCO-V6 65 GMC 2500 NAPCO Panel-V6 66 GMC 1000-V6 66 GMC 1500-V6 67 GMC K1500-SBC (originally a KM-V6) 68 GMC C1500-V6 68 GMC C1500-V6 68 GMC Suburban C2500 70 Chevy K20-SBC 71 Chevy C30 Longhorn-SBC 72 GMC Suburban C1500-BBC 72 Chevy C10-SBC 72 GMC C5500-ToroFlow Diesel |
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#15 |
Registered User
Join Date: Jun 2004
Location: Beeville, Texas
Posts: 1,943
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There's hardly anything about C20's in the resto pack I got. It covers mostly C10s, but I have a lot of the dealer manuals and parts books for the 10 thru 60 series trucks, this is the most recent book I have, got it for free too!
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RJD 1984 Chevrolet C30 welding truck 454/SM465 1977 GMC C15 pickup 350/TH350 1970 Chevrolet C20 pickup 350/TH400 1970 Chevrolet K20 Suburban 454/TH350 1969 GMC 8500 478M V6/5 spd winch truck |
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#16 |
Registered User
Join Date: Oct 2003
Location: Central Vermont
Posts: 8,538
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Here's a link for alot of frame info/specs for ya.
http://www.chuckschevytruckpages.com/framespecs.html |
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