UPDATE II (01/22/2024):  A puzzle has been solved. It was the Transport Motor Company that offered a full-width body extension that we’ve seen on several jeeps over the years.

This excerpt is from this document on Farmjeep.com: https://www.farmjeep.com/lifts/other-hydraulic-lifts/transport-motor-company-tmc-hydraulic-lift/

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UPDATE (09/13/2020): This DENCO body extension brochure appeared as part of the 10/01/1949 Second Supplement of the Willys-Overland Equipment Book brochures. 

Interestingly, the 1948 First Supplement of brochures showed a Newgren collapsible body extension (see a few brochures down or click here) very similar (identical?) to this 1949 DENCO Body Extension brochure. Both extensions offer 7 cubic feet of space and note that a spare tire can be mounted to the side. They also both seem to have the same style of stabilizer bar that connects to the PTO bar. I wonder if Newgren sold this design to Denco in late 1948 or early 1949?

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UPDATE 04/28/2020: Someone in Georgia is selling newly built beds.

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Originally published in 2016: This may come as a surprise (not) that early jeeps weren’t known for their vast amounts of space. We’ve all seen military photos showing jeeps packed full of stuff, like this SAS desert fighter:

When the war ended and CJ-2As were introduced, a couple companies recognized the need for more room and solved the problem by creating add-on bed extensions (also known as bed extenders and body extensions). These bolted to the back and, usually, had supports that dropped to the PTO bar to help support the extra weight. Then, the tailgate was fixed to the very rear of the extension. The goal of this post is an effort to identify the different companies and their products.

As early as August and September of 1946, two different patents were filed, both by the same people.I have been unable to discover if that first patent model was ever built, but the second one has two sides that fold down similar to the Newgren (shown in #2).

See more patent pages here.

Various Bed Extensions identified so far:

1. Porter Reed Bed Extension: One of the earliest known bed extensions was produced by Porter & Reed. It was marked along with a half top, creating a truck out of a jeep.
   
   
2. Newgren Bed Extensions: The Newgren Company also entered the bed extension field in the later 1940s with two different versions. The first was their standard bed extension:
   The second model Newgren offered was a collapsable version.
   
3. S & B Corporation’s Jeep Panel Body: About the same time Newgren and Porter & Reed introduced their extensions, the S & B Corporation made their own spin on adding more room by selling a kit that converted the jeep into a panel van.
   
4. Koenig Bed Extensions: By 1955, Koenig had entered the market. Whether the company designed their own or bought out one of their competitors isn’t know (to me), but Koenig sold the extensions for at least a decade. This first ad is from 1955, the second from 1960, and the third from the mid-1960s.
   
   
   Here is an example of a Koenig data plate:
   
5. Wall & Borg Bed Extender: In the 1960s, a Lake Tahoe, California, company called Wahl & Borg introduced a unique bed extension. Rather than bolt on to the rear of the jeep, theirs slid out.
   
   

There have been a number of bed extensions that have resold over the last ten years on Craigslist and eBay, some attached to jeeps and some by themselves. I have found it difficult to distinguish between them, never having owned or seen that many up close. You can see all the ones documents thus far on eWillys: http://www.ewillys.com/tag/bed-extension/

Derek Redmond also has some excellent information on extensions over at the CJ-3B Page. https://cj3b.info/Tech/BodyExtension.html