One thing we really love about the diesel industry, as it has developed over the past few decades, is the wide adoption of the power plant as an alternative swap for and into almost anything. A decade ago, Doug Brarens was a gasoline only person, but about five years ago he made the move to putting a diesel in a car and today is full-on diesel only guy through and through.
Brarens’ latest creation, which has been turning a lot of heads over the past year, is this little ’39 Chevy rat rod drag truck. We first saw it at the NHRDA World Finals in 2012.
When this year’s World Finals rolled around, we were definitely hoping that Doug would make the haul from Pennsylvania to Texas again. Thankfully he did and we jumped at the opportunity to shoot it for a feature and showcase all of the finer points.
Brarens loves old trucks and has been horse-trading projects and building rat rods for a very long time. So, when he decided it was time to “retire” (that’s what he calls it, but he hasn’t stopped building and we doubt he ever will) he knew exactly what he wanted to do. He likes to hold onto stuff and happened to have this little 39’ in the collection out back. It was a 1/2-ton long bed pickup that needed a lot of love before it would be anywhere near roadworthy.
So, the first thing Brarens did was decide on and locate a power plant that he would build the truck around. He searched junkyards and military surplus outlets until he came across exactly what he was looking for. He bought a 1991 Dodge D250 Army Tug truck. These were stout trucks that had solid power plants. He pulled the 12-valve Cummins out of it and sold the rest of the parts he didn’t need. From there, he started laying out the chassis.
(Left) It is all business under the bonnet. The 12-valve Cummins takes up every inch and then some. (Right) The Ford Pinto front suspension is a go-to choice for Brarens as he has built quite a few rat rods over the years.
Brarens, also known as the “metal man”, built a custom 2×3-inch boxed frame. To keep the frame off the ground, he picked up a Pinto (yes, we said Pinto) front suspension with a manual rack out of a scrap yard. He purchased a Jegster 4-link rear suspension kit to control the 9-inch rearend he found. Then he hung tuned QA1 coilovers on all four corners. This gave him a complete rolling chassis with power plant and performance suspension.

A tilt front clip is a rare sight, but a cool mod none-the-less. With the low stance, this was a challenging endeavor, and barely clears the custom RBP front grille by a hair.
Onto the body, Brarens set the cab about three inches off the ground and then built a full roll cage. With nothing in his way, he was able to easily make sure the welds were sound and everything was fully welded together. With the cage in, it was time to build a new floor, transmission tunnel, firewall and reskin the doors.
With the cabin complete, his focus turned to the front clip. Being an experienced mechanic, he knew that having easy access to the engine is very important. So, Brarens decided to build a tilt-up front clip. It turned out to be a little tricky but he eventually got the geometry correct and it was fully functional in no time. With the front fenders (chopped two inches) welded to the hood and the custom one-off Rolling Big Power (RBP) grille attached, the entire assembly swings up and out of the way for easy access.
On to the back! Since the truck was originally a long bed, Brarens knew that for both looks and function he would need to remedy the length and help ensure proper weight transfer at the same time. To kill two birds with one stone he shortened the wheelbase down and ended the bed just after the wheels. His vision and passion for old trucks really shows with the forethought put into building the bed, front end and all the neat little tricks throughout.
This is a perfect example of having a clear goal in mind and working hard to meet that goal. Instead of spending a ton of money to upgrade the engine, Brarens upgraded the key components to produce enough power to run the quarter in 11 seconds flat (his goal from the very beginning).
DA "Spec Box" - The Goods
Owner Info:
- Name: Doug “The Metal Man” Brarens
- Job: Retired (yet still builds and sells diesel rat rods)
- Truck: 1939 Chevy Pick Up
- Best time/speed: 11.40 at 116 mph
Powertrain:
- Engine: 12V Cummins
- Transmission: 727 Torqueflite
Chassis:
- Front Suspension: Pinto
- Rear Axle: Ford 9-inch
With a solid roller, he turned his attention to building a little power in the old 12-valve. First thing he did was fix the dowel pin issue (in the early 12v engines, the dowl pin holding the front cover can fall out and take out an engine), then turned his attention to the fuel system. An Airdog fuel pump supplies the fuel factory injection pump with the fuel it needs.
Instead of running a big expensive injection pump, Brarens knew that a truck this light (3,010 pounds) didn’t need a ton of power to go fast (runs 11.30 at 116 mph in the 1/4). So, he modified the fuel pin and upgraded the governor spring. For injectors, he opted to go with a set of Stage 3 injectors. To supply enough air for this setup, he upgraded to a HE351 Holset turbocharger. The turbocharger runs through an intercooler he found on an old Isuzu cabover truck. Outback a 7-inch Assie stack from Powerflow was the perfect choice.
With the engine dialed, it was time to focus on the rearend. He installed a spool with a 2.49:1 gear ratio. A set of Moser 33-spline axles turn the 15-inch Centerline Auto Drag wheels wrapped with Hoosier 31×16.5R15 tires.
To stop everything at the big end of the track, a weld-on disk brake conversion kit was used in the rear and in front a Wilwood disk brake conversion kit handles the stopping duties.
Many people don’t quite understand builds like this. Just because the truck is a rat rod style build, doesn't mean there isn't attention to detail throughout. This truck is full of little details that are both cool and subtle.
On the interior, things are a little tight. So, to keep his eyes on the track as much as possible, Brarens opted for a set of Auto Meter’s Cobalt gauges. These have a lot of contrast and makes it easy for him see what is going on quickly. Controlling the gears in the 727 Torqueflite transmissions is easy thanks to a B&M pro stock shifter.
All said and done, this little rat rod is definitely both go and show and gets the job done. Small budget, fast and fun diesel truck – exactly what Brarens set out to do from the beginning.
In small light weight vehicles weight transfer is important. With the engine weighing in at a third of the weight of the truck, moving the fuel tank, battery, and miscellaneous parts to the rear helps to plant the big Hoosiers.