Weld box frame to chassis or U Bolt?
 

So working through the planning stages and need some opinions....

We are planning to mount a dry van box to the Volvo chassis, would you weld it or would you U Bolt it? My thought is to weld it solid as it makes doing side storage boxes easier but their may be drawbacks as well....

Wouldn't do either, U bolts aren't strong I would weld a bracket on the side of the chassis not on the flange, never weld on the flange. Then weld another bracket and bolt the two together or you can weld one bracket on the box and bolt it to the chassis going through the side not the top flange of the chassis/channel iron frame. Welding it solid will make the welds pop as tension has to be released somewhere when it flexes. Had an F450 previous owner welded the flatbed to the truck, that didn't last long, popped the weld several times till I could bolt it down. Use grade 8 fine thread a 5/8 bolt or bigger is best and put a board, HDPE plastic shim or something between the box and the frame thin as possible to prevent squeaking of metal to metal.

I see were your going with this....so welded tabs on the box or frame that bolt for securement....thanks for the info.

You're welcome

re:
the 'U' bolt system to attach components to a commercial frame
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This's the standard method of attaching irregardless of component.
The 'U' bolts around the frame can attach:
* a tank body, or
* a flatbed, or
* a dump aka 'tipper', or
* a dry van.
Dimensions of a commercial truck frame are standardized, allowing a retired semi to be re-roaded as a cargo-van or dump-truck.
As the road-worthiness approaches 'kaputt', that same old truck can carry an off-highway water-tank for construction projects.
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So, 'yes', attach your dry van box using 'U' bolts.
You can buy these to your specifications at an installer of truck bodies.
Measure, take photographs, take your dimensions to the installer:
* they place the straight threaded rods in the bender, and suddenly!,
* you have four or six big honking 'U' bolts to secure your dry van box to your frame.
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For a semi-tractor, the fifth-wheel hitch is attached with a massive number of massive bolts.
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But 'U' bolts from a hardware store?
Probably on the skimpy side.
.
.
2003, we converted a 1997 Ford CF8000 commercial truck to our concept of an ExpeditionVehicle.
2010, we converted a commercial trailer to our concept of a toy-hauler.
Each of these carried different bodies/components prior to coming home to our welcoming arms.

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See if your area has a heavy-truck dismantler aka 'wrecking-yard'.
In Eugene Oregon, we have Anderson Brothers Truck Wrecking, a walk-through museum of junked trucks and truck bodies.
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In Eugene Oregon, for those custom-bent 'U' bolts engineered to attach truck equipment to commercial frames, we have Kaiser Brake And Suspension.
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Post photographs of your progress!

Thanks for the info Sir and i will post up photo's as soon as i kick this project in high gear.

Alright, let the games begin (sorry i travel for a living so things move very slowly sometimes).....finally got the 10 foot doner frame and support plates all cut, fitted, bolted up. (Before anyone says anything its surface rust i live in a 4 season area and our goverment loves salt for winter roads)
Next will be to have someone come and weld it together. (I can weld but this is a job for a certified welder).

The following stage, after welding will be to move the axles back one position, so front to the rear position and rear back the equal amount. When said and done it will leave us about 6.5ish feet of over-hang.