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#1 |
Registered User
![]() Join Date: Oct 2006
Location: Southern Kalifornia
Posts: 3,066
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Is there any way to tell if a truck originally came with a big block? I have a 1972 c20.It has the 8-400 emblems on the front fenders,the right frame towers,a th400,dana 60,front/rear sway bars,disc brakes,p/s,had cruise control. The cab has a low hump.
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#2 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Original Big Block Truck?
Is the option sheet still in the glove box?
Look under the hood, passenger side down low on the firewall. You're looking for a head shield. That is a big block truck only piece. If you don't have a build sheet, nor option sticker, you can only go by what is there. Now... on that cruise control... do you plan on getting it back together... or would you be willing to sell some of it? |
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#3 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,553
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Re: Original Big Block Truck?
What about the glovebox sticker? With the emblems I would guess big block
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#4 |
Senior Member
![]() Join Date: Aug 2003
Location: Conyers,Ga.
Posts: 7,287
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Re: Original Big Block Truck?
Low hump is probably strike 1.
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#5 |
Senior Member
Join Date: Aug 2003
Location: Lubbock, Texas
Posts: 2,443
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Re: Original Big Block Truck?
With a low hump, I would say small block.
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72 Cheyenne Super 80 Silverado Blazer 2wd |
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#6 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,553
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Re: Original Big Block Truck?
Not always, I have had 2 trucks now with 400s and low hump. My current one is a 69 GMC 30 series--started life as a class B motorhome ---small hump
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#7 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Original Big Block Truck?
and if it was a 3 speed manual, it woulda had a low hump, but i too have seen a few low hump 402/Th400 trucks.
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#8 |
Senior Member
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Location: Conyers,Ga.
Posts: 7,287
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Re: Original Big Block Truck?
Factory dual exhaust with hangers riveted on? Isn't the fuel line larger also? If it's a coil spring truck, alot of the big blocks had a brace running from the frame to the support that the trailing arms bolt to.
Last edited by uncle; 11-05-2006 at 10:16 PM. |
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#9 |
Senior Member
Join Date: Aug 2003
Location: Lubbock, Texas
Posts: 2,443
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Re: Original Big Block Truck?
Long shot , but it might have the emission control sticker on the drivers inner fender.
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72 Cheyenne Super 80 Silverado Blazer 2wd |
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#10 |
Registered User
Join Date: Feb 2004
Location: Tacoma WA
Posts: 1,365
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Re: Original Big Block Truck?
If the SPID on the glove box is gone, look at the back of the seat on the passenger side for the build sheet. Usually under the springs and almost impossible to remove whole. If it's there check the VIN to make sure the seat hasn't been changed.
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67 C-20 LWB, tilt, speed alert, vac, 454, T400 67 C-10 SWB, factory air with more to follow |
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#11 |
Registered User
Join Date: Jan 2001
Location: Lincoln, Nebraska
Posts: 2,145
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Re: Original Big Block Truck?
The C20 402 automatic only used a 3:54 gear ratio.
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#12 |
Registered User
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Location: Southern Kalifornia
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Re: Original Big Block Truck?
WOW! now I'm really confused. It has part of the emission sticker that says 402,as far as the heat shield will have to look tomorrow.Thanks Guys.BTW it is a custom camper.
Last edited by manimal; 11-06-2006 at 12:13 AM. |
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#13 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Original Big Block Truck?
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#14 |
Senior Member
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Location: Los Angeles
Posts: 1,332
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Re: Original Big Block Truck?
Big Block TH 400 shorts had the high hump, but I think the long beds used the low hump. Something about raising the transmission to correct the driveshaft angle?
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1967 GMC CM-2500 Camper Cruiser, 351E V-6, NP 435 4 speed, Dana 60, and factory A/C. 2012 GMC K-3500 WT regular cab, 6.0L Vortec, 6L90. |
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#15 |
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Location: Spokane , Wash.
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Re: Original Big Block Truck?
My 68 bb t400 long box has the high hump , as does my 70 bb 4 speed . What about remote resevoir p/steering pump , all my bb have had these .
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Can-Am Motorsports 37 Chev Coupe 331 4 speed 5.13 posi . ex-gasser . 64 Biscayne 409 2x4 4 speed 4.11 posi 65 Nova Wagon Drag Car 383 t400 (Dragin-Wagon) 68 c10 cst 396 t400 a/c buckets lwb 4.11 posi (SOLD) |
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#16 |
Senior Member
Join Date: Aug 2003
Location: Lubbock, Texas
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Re: Original Big Block Truck?
Did all bb come with a TH 400, or could some of them come with a TH 350?
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#17 |
Senior Member
Join Date: Jun 2001
Location: Shelbyville, KY
Posts: 3,269
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Re: Original Big Block Truck?
The one constant of a big block cab is the exhaust heat shield on the lower part of the firewall---passenger side. Hump size was transmission dependent to my knowledge. The other key as mentioned would be the power steering --assuming it had that--you would have a couple of extra holes on the upper inner drivers fender where the windshield washer tank would normally mount. This would be for the PS resevoir. If the heat shield is there, it was a big block.
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#18 | |
Registered User
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Location: SOMERSET KY.
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Re: Original Big Block Truck?
Quote:
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#19 |
Registered User
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Location: Southern Kalifornia
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Re: Original Big Block Truck?
Well no heat shield but there was an "add on"a/c on the truck when I bought it. The hoses ran right where the heat shield should be. The original fender has the extra holes for the resevoir but has been changed to pump w/res. Oh Well I got a smokin deal on the truck anyway and other than eating flexplates and starters I havent been left stranded.
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#20 |
Java Mechanic
Join Date: Jun 2005
Location: Martinsburg, WV
Posts: 6,764
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Re: Original Big Block Truck?
For more confusion ... I thought the 400 emblem refered to the small block, not the rat. Isn't the 396 labled as a 402 in those years in trucks?
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Keith 11 Lincoln MKT -- Momma's wagon ![]() 13 G37xS -- middle age crazy car 68 C20 Fleetside -- RIP Decorating the whole town up at a cost of $27 .... |
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#21 |
Registered User
![]() Join Date: Oct 2006
Location: Southern Kalifornia
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Re: Original Big Block Truck?
Yeah the 396 became a 402 but the emblems refer to it as a 400 big block.
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#22 |
Senior Member
Join Date: Aug 2003
Location: Lubbock, Texas
Posts: 2,443
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Re: Original Big Block Truck?
The 400 emblems were for the bb. I didnot think there was a 400sb in these trucks. I have seen several original old trucks where the glovebox said 396, the fender emblem said 400, and the emission sticker under the hood said 402 all on the same truck.
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72 Cheyenne Super 80 Silverado Blazer 2wd |
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#23 |
Java Mechanic
Join Date: Jun 2005
Location: Martinsburg, WV
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Re: Original Big Block Truck?
OK.. I'll blame the confusion on how many of US like to put 400sb mills in trucks..
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Keith 11 Lincoln MKT -- Momma's wagon ![]() 13 G37xS -- middle age crazy car 68 C20 Fleetside -- RIP Decorating the whole town up at a cost of $27 .... |
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#24 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: Original Big Block Truck?
lol, that is true. the first 400 small block in the trucks was 73 if I'm not mistaken.
And there were no 396 engines built after 69, they were all 402 from 70 on up. |
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#25 |
Senoir Member
Join Date: Mar 2002
Location: Rock Hill, SC USA
Posts: 1,214
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Re: Original Big Block Truck?
My 70 GMC C-10 has the factory 402, T400, High hump....came with glove box sticker & build sheet. All numbers match and there is NO heatheat on the passenger side. Greg
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67 Chevy, Small back glass, Factory 4WD, Factory Shortbed, Factory V8, Lifted 4" 70 GMC Sierra Grande, Factory Shortbed, Factory 402/400 turbo, Super Custom Interior. Numbers matching with SPID & Build Sheet. 68K Original Miles. Restored 2010 70 GMC Restoration Pictures http://67-72chevytrucks.com/gallery/...00&ppuser=4424 |
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