66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mehtwo · 01-30-2010, 04:09 AM

I'm in the planning stage of building a 1966 GMC heavy-duty 1-ton(maybe a 1-1/4 ton?) crew cab dually. I want to use a 478 GMC v-6, a fuller FSO-6406a 6-speed manual O/D transmission, a dana 70hd or dana 80 rear(with 3.55, 3.73, or 4.11 gears). Because the 478 weighs a lot(925 lbs dry!) I wanted to know if a 73-91 1-ton coil spring suspension and frame are stout enough for this engine and trans. If not, I would like to know if a p-30(?) front suspension and frame would be sufficient using either the coil or leaf spring front end. I've been partial to the 19.5" wheel with the 5/10 lug on 7.25" pattern, but it's not absolutely necessary. I'm looking at using 32-33" diameter tires. I want to use this rig strictly for towing 22,000 or less pounds cruising around 65-75 mph on flat land. I plan to use this rig to replace my 86 chevy crew cab 1-ton dually that has a 454, th400, 4.11 rear. The bottom line is that I want an older GMC equivalent(more or less) of a new f-450 pickup. Any help or advice is greatly appreciated.

Mike

Long live the V-6!!

jonzcustomshop · 01-30-2010, 08:22 AM

how are you going to do the cab? already have one, or building one?
here is a pic of a BIG crewcab

mehtwo · 01-30-2010, 11:55 AM

That looks cool!

I plan on using a 1964-1966 cab for the front part and a 1960-1963 cab for the rear and modifying the 1960-1963 doors accordingly. I also don't want to have exposed rear door hinges.

Mike

62gmc910 · 02-02-2010, 10:20 PM

I thought there would be a little more input than this one of the v 12 trucks is on http://67-72chevytrucks.com/vboard/s....php?p=3686007

mehtwo · 02-03-2010, 10:31 AM

?????

62gmc910 · 02-03-2010, 02:14 PM

You asked if the front suspension would handle a big V6 , Rap'em Pappy and cayoterun run V12-702 engines

mehtwo · 02-03-2010, 08:21 PM

I'm concerned if the suspension would handle the 478 engine(925 lbs dry), the transmission(345 lbs), the bellhousing(???lbs), and handle the strains & stresses of pulling around 22,000 lbs on a gooseneck.

mehtwo · 02-20-2010, 12:40 PM

I'm now considering using a 2-ton frame(from the 1960-1966 era) with 1 ton or 1-1/4 ton suspension while keeping the light-duty(1/2-1 ton) front sheetmetal. Any thoughts on this?

100%Chevy · 02-20-2010, 10:34 PM

The stiffest springs for 73/91 are those for the diesel trucks,and still not stiff enough.
P-30,C-30 and G-30 are more or less the same.
Coyoterun used a Ford 1 ton frame,but he ain't pulling 22,000#'s.
Think 22,000 pounds is 11 tons!
I'd use the 2 ton suspension.
Mike.

01-30-2010, 04:09 AM	#1
mehtwo Registered User Join Date: Jan 2010 Location: Southeastern NM Posts: 12	66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab I'm in the planning stage of building a 1966 GMC heavy-duty 1-ton(maybe a 1-1/4 ton?) crew cab dually. I want to use a 478 GMC v-6, a fuller FSO-6406a 6-speed manual O/D transmission, a dana 70hd or dana 80 rear(with 3.55, 3.73, or 4.11 gears). Because the 478 weighs a lot(925 lbs dry!) I wanted to know if a 73-91 1-ton coil spring suspension and frame are stout enough for this engine and trans. If not, I would like to know if a p-30(?) front suspension and frame would be sufficient using either the coil or leaf spring front end. I've been partial to the 19.5" wheel with the 5/10 lug on 7.25" pattern, but it's not absolutely necessary. I'm looking at using 32-33" diameter tires. I want to use this rig strictly for towing 22,000 or less pounds cruising around 65-75 mph on flat land. I plan to use this rig to replace my 86 chevy crew cab 1-ton dually that has a 454, th400, 4.11 rear. The bottom line is that I want an older GMC equivalent(more or less) of a new f-450 pickup. Any help or advice is greatly appreciated. Mike Long live the V-6!!

01-30-2010, 08:22 AM	#2
jonzcustomshop 1961 crewcab Join Date: Dec 2007 Location: missoula, mt Posts: 6,164	Re: 66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab how are you going to do the cab? already have one, or building one? here is a pic of a BIG crewcab Attached Images __________________ 60 build: http://67-72chevytrucks.com/vboard/s...d.php?t=280904 61 crew build: http://67-72chevytrucks.com/vboard/s...d.php?t=646830 63 build: http://67-72chevytrucks.com/vboard/s...d.php?t=336537 64 'burb build: http://67-72chevytrucks.com/vboard/s...d.php?t=448681 65 'burb build: http://67-72chevytrucks.com/vboard/s...d.php?t=590715 65 build: http://67-72chevytrucks.com/vboard/s...d.php?t=281955

01-30-2010, 11:55 AM	#3
mehtwo Registered User Join Date: Jan 2010 Location: Southeastern NM Posts: 12	Re: 66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab That looks cool! I plan on using a 1964-1966 cab for the front part and a 1960-1963 cab for the rear and modifying the 1960-1963 doors accordingly. I also don't want to have exposed rear door hinges. Mike

02-02-2010, 10:20 PM	#4
62gmc910 Registered User Join Date: Nov 2009 Location: Cremona AB Canada Posts: 370	Re: 66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab I thought there would be a little more input than this one of the v 12 trucks is on http://67-72chevytrucks.com/vboard/s....php?p=3686007 __________________ 62 GMC 910 short fleetside 454 super t10 14 bolt w/gov lock 70s c20 front discs (built in the 80s) 65 GMC 930 dualwheel 292 4spd all origonal 39k mi(my sons truck) 63 GMC 950 camperized school bus, (Gus the bus) 350 4speed 2 speed rear 64 GMC 950 "spare" bus 283? 4speed detroit locker 53 GMC 1ton dual wheel bus 78 GMC c25 short course off road race truck(son's truck) 355 th400 14 bolt (www.wheel2wheel.ca) 88 Peterbilt 379 longhood (hauls race truck)

02-03-2010, 10:31 AM	#5
mehtwo Registered User Join Date: Jan 2010 Location: Southeastern NM Posts: 12	Re: 66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab ?????

02-03-2010, 02:14 PM	#6
62gmc910 Registered User Join Date: Nov 2009 Location: Cremona AB Canada Posts: 370	Re: 66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab You asked if the front suspension would handle a big V6 , Rap'em Pappy and cayoterun run V12-702 engines __________________ 62 GMC 910 short fleetside 454 super t10 14 bolt w/gov lock 70s c20 front discs (built in the 80s) 65 GMC 930 dualwheel 292 4spd all origonal 39k mi(my sons truck) 63 GMC 950 camperized school bus, (Gus the bus) 350 4speed 2 speed rear 64 GMC 950 "spare" bus 283? 4speed detroit locker 53 GMC 1ton dual wheel bus 78 GMC c25 short course off road race truck(son's truck) 355 th400 14 bolt (www.wheel2wheel.ca) 88 Peterbilt 379 longhood (hauls race truck)

02-03-2010, 08:21 PM	#7
mehtwo Registered User Join Date: Jan 2010 Location: Southeastern NM Posts: 12	Re: 66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab I'm concerned if the suspension would handle the 478 engine(925 lbs dry), the transmission(345 lbs), the bellhousing(???lbs), and handle the strains & stresses of pulling around 22,000 lbs on a gooseneck.

02-20-2010, 12:40 PM	#8
mehtwo Registered User Join Date: Jan 2010 Location: Southeastern NM Posts: 12	Re: 66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab I'm now considering using a 2-ton frame(from the 1960-1966 era) with 1 ton or 1-1/4 ton suspension while keeping the light-duty(1/2-1 ton) front sheetmetal. Any thoughts on this? Last edited by mehtwo; 02-20-2010 at 12:51 PM. Reason: forgot a few words

02-20-2010, 10:34 PM	#9
100%Chevy Registered User Join Date: Jun 2008 Location: Moss Point,Ms. Posts: 1,439	Re: 66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab The stiffest springs for 73/91 are those for the diesel trucks,and still not stiff enough. P-30,C-30 and G-30 are more or less the same. Coyoterun used a Ford 1 ton frame,but he ain't pulling 22,000#'s. Think 22,000 pounds is 11 tons! I'd use the 2 ton suspension. Mike.



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