With the popularity of the '67-'72 GM trucks still holding strong, it's seems nearly impossible to find a good clean shortbed truck to restore. Anyone lucky enough to own one has a dozen stories of people chasing them down and trying to buy their ride out from under them. They can usually produce a few windshield notes and business cards left by prospective buyers, as well. On the other hand, there seems to be a plentiful supply of longbed models still floating around, and many savvy builders are constructing the truck of their dreams by acquiring a longbed and shortening up the chassis.
Now, this seems like a giant undertaking, but truck frames are shortened and lengthened every day to accommodate different applications in the big truck industry. The same techniques can be applied to the light truck market with great results. In this story, we'll follow along as Early Classic Enterprises cuts out about 20 inches from a '71 C20 3/4-ton truck. If you are really good with a welder, you can cut down the bed's sheetmetal, but luckily, there is an option that requires a little more money but a lot less work. ECE sells a new reproduction shortbed kit that comes with everything you need to complete the shortening. If you are having trouble finding the shortbed truck of your dreams, then read these words and see if you want to shift your search to a longbed. Happy hunting.
Chop It!
The '60-'72 GM light-truck series had several wheelbase options, the two most popular being the shortbed at 115 inches and the longbed topping out at 127 inches. Over the years, many longbed chassis have been shortened, and the process is not that complicated. Shown here are two bare frame examples. You can see that not only is the length different but also the placement of the various crossmembers. | 
The rear framerails can simply be cut off and do not require any welding or other modification. The rear of the frame needs to be shortened 8 inches, and a Sawzall will make quick work of the job. |  |
Shortening the center of the chassis is substantially more involved. The frame needs to be literally cut in half, 1 foot removed, and the front and rear frame sections welded back together. In other words, it's not a project for the faint of heart. Alignment of the frame sections is also a critical procedure, and failure to do so properly could mean the difference between a sweet shortbed chassis and a pile of junk. After the frame is fixed on a level floor using jackstands, the cab mount bolts are removed to allow the cab to be raised up from the frame for clearance (inset). All of the plumbing and the wiring need to be removed before the frame can be cut. |  | 
This extra bed mount has to be removed; it is not needed for the shortbed. Use a cutoff wheel to grind a line down the middle of the rivet and then pop it off with an air hammer. |
The center of the frame needs to be shortened by exactly 12 inches under the cab area. | 
After scribing a 45 degree line, the front scribe line is cut using the Sawzall. | 
By blocking the front and center of the frame, the rear section is able to roll back away from the cab to make the rear cut easier to access. |