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!!
:gmc2:

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

Re: 66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab
 

That looks cool!:metal: 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

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

Re: 66 GMC Heavy-duty 1 ton(1-1/4 ton?) Crew cab
 

?????

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

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. :sumo:

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?

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.