Shortboxing the Frame

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I like short box trucks.  I know, they’re less practical.  Boo hoo.  I like them.

We pulled the box off the truck (sorry, no pics in one piece).

Truck Pictures 2s

Truck Pictures 1s

Initially, we were going to chop up and scab a short box out of the old long box.  The box was very pooched (this pic was after we stripped the box).

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I had bought replacement wheel arches to try and piece this piece back together, but it was not meant to be.

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We found a short box locally for very cheap. Not in very good shape, but salvageable.

Then came the frame.

There are a variety of methods to cut the frame (all of which need to be fish-plated):

I chose the vertical cut, because the required 14″ section didn’t leave enough room to fish-plate effectively without removing the rear cab mount and front leaf spring mount. So… laziness made my decision for me. It will work.

Truck Pictures 3s

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14″ were cut out just behind the forward cab mount. I think I went 7″ off the cab wall. Try to have the resultant weld join centered between the cab mount and the leaf spring mount.

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Outer welds were ground smooth so as to be less noticeable from the outside. You can see the Heat Affected Zone (HAZ) of the fish plate (I used the 14″ section for the fish plate).

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Here you can see the fish plate. I chose to do a diamond, so the entire plate can be welded. Some people choose to do a rectangular plate – in which case ONLY weld the top and bottom (horizontal) edges, NOT the vertical edges. Existing holes became plug welds.

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5″ are cut off the back of the frame. Some people cut 6″ but 5″ is fine. It’s easy enough to cut it shorter – hard to put it back.

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New box mount is located right here – to be drilled 9/16″. There is a slotted hole in that location in the crossmember riveted below.

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Rear crossmember is relocated to existing holes in the frame, and the outer of the two old rivet holes are drilled to 9/16″ for the box mount.

We bought a new 16 gallon shortbox tank.

We had a driveshaft custom made (56″, 1310 ends, 3-1/2″ diameter), which later turned out to be a piece of garbage

Once the truck was on the road, there was a fair bit of driveline vibration. I put in new Precision brand u-joints within the first year, then replaced those with Spicer within the next year, then replaced them again. I balanced the wheels, flipped tires, balanced the brake drums, change the transmission mount height, and finally when I put in a rebuilt 3.73 axle everything shook from 60kmh up.

I went through it all again, and eventually the shaking subsided to a butt-wiggle at 80km/h only, until a ring gear bolt worked its way loose three years later and jettisoned out the diff cover and I had the rear end rebuilt again, then all the death shakes 60kmh and up came back.

I gave up chasing it (it was defeating me) and “paid the man,” who found that the yoke castings on the driveshaft were BADLY cast, and they made me a new driveshaft. OMG was it a ton better!  “The Man” was Truckworks out of Kelowna – I am pleased!

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This is not the Truckworks driveshaft; this was a poop driveshaft.

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Entire frame was de-scaled and painted with Zero Rust paint.

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Bed underside was de-scaled, painted with Zero Rust, sprayed with undercoating, and attached with new fasteners.