Is the 1988 F350 dually currently with a flatbed able to be fitted with a dually box. I assume that the frame length is the same too.

 

If it started out life as a pickup, yes. If it is a cab & chassis truck, then it would require pretty extensive modifications to the pickup box.

 

Thank you.
How would I know by looking at the truck if it was a factory pick-up? Are there any specific things to look at on the frame? I also think the VIN says wouldn't it?

 

Easiest way to look at the frame over the rear axle. Cab & Chassis trucks have frame rails that are dead flat from the cab to the rear of the frame rails, narrow right behind the cab, then go straight back to the rear bumper. Pickups will have a bit of a hump over the rear axle, somewhere around 2 or 3 inches, and don't narrow behind the cab. Somewhat similar to the C-notch the lowered guys will do to get the extreme drops, but nowhere near as pronounced.

 

I didn't look at the vehicle yet, but I got the VIN from the owner. It says it was shipped as "incomplete vehicle" and also F38 in the third position of the VIN which apparently means "cab and chassis" from a VIN check on the web. So it looks like, as you said is that it would require extensive modification to fit a dually pick-up box on it.

 

Can anyone discuss in some detail what "Modification" to the dually box is required for this installation.
I am planning to do the same swap to my 1990 F350 4x4 dually and I have a dually box available to use but would like to know beforehand.
Thank you, Pete

 

If it's going on the cab and chassis truck, the big thing is going to be sectioning the wheel wells inside the bed farther to clear the inner duals. You also likely will need to narrow the outside flares a similar amount to look right.

 

also need to make new bed bolt mounts, and stretch the bed to fit the longer frame.

 

A ten? foot bed that never has to be made would be pretty neat

 

years ago i took a picture of a chevy pickup with a 14 foot pickup box. unfortunately photobucket is holding it hostage, and i refuse to pay them to release my pictures.

 

You do NOT need to section the wheel wells to put a dually bed on a dually cab n chassis.


Now, for what the differences are between a pickup and a cab n chassis

Regular cab 8 bed pickup is a 133" wheel base
Regular cab standard frame cab-n-chassis is 137" There was an optional 161"
So that mean the cab n chassis is 4" longer so you would have a 4" LARGER gap between the cab and bed than what should be there.

Pickup frame rails are 37-3/4" wide
Cab-n-chassis are 34"
So you would need to drill holes inside of the factory bed mounting bolts by 1-7/8"
OR make brackets that would bolt to the bed and then run down and bolt to the side of the frame
The rear bumper would face a similar problem and you would need to make spacers between the brackets and the frame

I do not remember the exact numbers for the c-n-c but it is a ball park
Dually cab n chassis axles are about 4" narrower than a dually pickup axle
A dually pickup axle is 72.75" from wheel mounting surface to wheel mounting surface.
So that would make the c-n-c axle about 68.75"
that in turn would leave your outer dually tires tucked under the dually pickup like a railroad truck


Anything else you would like too know? I would be more than happy to help.

this is 1st hand info since I have done it a couple times

 

Hey Folks,
Thanks Diesel_Brad for the Post #11 update and detail infomation.
All your points match my notes regarding the Cab & Chassis; however, my wheelbase measured slightly more than 138".
I roughly installed the dually box to center the wheel openings over the rear wheels and I had about 6"-6-1/4" gap b/w the cab & box so the "Box Extension" I designed and I'm fabrication will be about 5" to 5-1/4" once completed to provide me with a factory box appearance and a near factory gap as well.
I surveyed and I measured all the six box mounting points and found that I would relocate the front two box mount holes inward 2" on each side but the center box mount holes move inward a lesser amount because the center box bolts were offset (inward) slightly from the factory already. I decided to leave the rear bolt mounts alone and just add an extension plate outside the frame to create a similar 37-3/4" wide frame section to catch the rearmost box bolts without modifying the rear bolt mounts in the box. When I drilled the front & center box bolt holes in the dually box floor & crossmembers I also released the box bolt reinforcements welded inside the box crossmembers and moved them inwards to the new locations and rewelded them into position.
If I can post a photo or two of the 'Box Extension' I will try.
Hopefully no one will be offended in this post as I am not trying to hijack this post with my information.

 

The 5th, 6th and 7th digits of the 17 digit VIN decode to a Regular/Crew Cab Cab & Chassis or Pickup or a Super Cab Cab & Chassis or Pickup.