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1959 GMC 4X4 Truck Gets 4th Gen B-Body Chassis Swap

A customer that had recently purchased a 1959 GMC Truck, running, came to us wanting to update things a bit, modernize but keep it a hot rod — or a sleeper…

1959 GMC Before and After Undergoing a B-Body Chassis Swap
1959 GMC Before and After Undergoing a B-Body Chassis Swap

Project: 1959 GMC Truck / B-Body Swap and Cut to Short-bed

After talking to the customer about how he hoped to drive and use the truck, it was immediately clear that a late-model chassis swap was the best option for this build. The customer’s father-in-law happened to have on-hand a prime example of a perfect donor car: on-hand, low miles, and our favorite platform for swaps — perfect. Lets tear apart the 1995 Chevrolet Caprice Classic donor car…

Chassis and Drive-Train Donor: 1995 Chevrolet Caprice Classic

The Chassis / Body Swap in 60 Seconds

Watch the full Caprice Classic tear down, body swap, and GMC truck cab plant in this 60 second time-lapse video:

A lot of folks will tell you that chassis / Body Swap won’t work because the frame rail are too wide. Wrong. They are perfect. The cab steps make the cab too narrow. And therein lies the solution: 

To get the cab to fit around the wide B-body frame rails, cut the cab steps out from both sides as shown below (you are cutting the solid yellow lines). 

Once both sides are cut, take the passenger side cut out to the driver side, flip it so that it fits into the cutout in the convex orientation instead of its original concave orientation from the other side, and weld it into place, as shown below (we are looking for better photos of this step), thereby widening the cab by the cutout depth on both sides.

With the cab planted, the full, uncut harness (some segments have been eliminated; rear-doors, for example) is applied and anchored to the chassis…

We use the harness in full – end connectors are harvested during the tear down of the donor and used to install the harness back into the vehicle in the same plug-in fashion it came from the factory with. This also means that all systems are a go once things are reassembled.

The compass and map light in the rear-view mirror work, the stereo is wiring with the b-body harness, all of the aftermarket under dash A/C was wired int the original harness, making for not only a full featured vehicle, but one that is solid for a wiring point of view.

There are several tabs and lips that need to be shaved off for the cab to lay down cleanly. We used the original b-body body mount holes and holes in the cab to match, and mounted the cab with two stacked hockey pucks between.

Next to cut the fleetside bed down to short-bed length and put the wheel wells where we want them. 

Because of the fleetside bed, we opted to do all the wheel well movement below the line to prevent too much welding on the upper bed-side.

With the bed welded back together, body-worked and fade painted to match, we chose to blow the exhaust right out the side of the truck and let the Cherry Bomb exhaust sing to the world…

With the harness and computer tucked neatly and secured under the dash, the rest of the vitals can be installed…

…including the gauge cluster from the donor car. The headlight switch from the donor was used, and the twilight sentinel sensor placed so auto-on and off headlights function. 

The ’59 GMC Fleetside Burnin’ Out…

The Final Truck

The customer added some personalized paint, wheels, and interior touches…