Factory-built 4×4 pickups are produced in such vast numbers by a multitude of global manufacturers that we pretty much take them for granted today.
However, back in the 1950s such vehicles were a global rarity, which makes surviving examples of the little known ‘NAPCO’ Chevrolet and GMC (plus Ford and Studebaker) trucks produced during that era rare and desirable.
When World War II ended, the only new 4×4 one tonne pickup available to the private buyer in the USA was the excellent WDX Dodge Power Wagon first released in 1946; a civilian adaptation of the legendary WC series military truck that proved very popular.
Clearly, there would soon be great demand for similar 4WD pickups, as a plethora of public utilities and private industries began to flourish. Which is where ‘NAPCO’ comes in. Those five letters stood for ‘Northwestern Auto Parts Company’ which was established in 1918 in Minneapolis, Minnesota.
During WWII, NAPCO’s specialised automotive engineering skills had been focused on fulfilling military contracts for the US government. When hostilities ended in 1945, the company switched to production of automotive components for civilian and commercial use.
And one of those was the NAPCO Powr-Pak 4×4 conversion kit, neatly packaged in a robust 200cm x 76cm x 66cm wooden crate that weighed about 640kgs ready for shipping.
In the space of three hours and with only four mounting holes needing to be drilled into the chassis frame, the Powr-Pak could turn a humble 2WD pickup into a 4WD ‘mountain goat’ capable of tackling the toughest terrain.
The 4×4 kit had everything required for the swap, including a complete replacement front differential assembly (with no change to the standard turning radius), two-speed Spicer 23 transfer case, propeller shafts, wheels, brakes, shocks, everything. And most were GM-sourced parts, which made servicing a breeze for GM dealers.
No welding or gas-axing of the chassis was required. In fact, NAPCO guaranteed no damage to the chassis frame during the three-hour installation. It was a clever and simple ‘bolt-up’ job, using tried and tested components that were immensely strong and durable.
Private buyers and government departments could order a new pickup and a NAPCO Powr-Pak, which could be shipped anywhere and easily installed within a day by either a dealer or specialist aftermarket fitter.
Another great Powr-Pak attribute was that with its simple ‘bolt-on’ design it could be easily transferred from one truck to another. It also offered an engine-driven Power Take Off (PTO) option to run a winch and the transfer case was rubber-mounted for smoother and quieter operation.
The ability to switch from 2WD to 4WD whilst on the move was also claimed, although we have heard since that attempting such a shift-on-the-fly manoeuvre can result in lots of nasty crunching noises and expensive drivetrain damage! We are talking about the 1950s technology here, so that’s fair enough.
Although these 4×4 conversions were performed on Chevrolet, GMC, Ford and Studebaker vehicles, the name NAPCO is mostly associated with Chevrolet and GMC including ½ ton, ¾ ton, one and two two-tonners. There were also Suburbans and panel-sided vans in the mix.
Indeed, the Powr-Pak conversion proved so successful that it became a GM Regular Production Option (RPO 690) in 1957 and installed on the assembly line. And, not surprisingly, any reference to NAPCO was absent from that point, as shown above.
The NAPCO conversion era came to an end in the early 1960s, after GM did a complete redesign of its pickup truck range which included independent front suspension on the 2WD models (in place of the previous leaf springs/live axle arrangement) and introduced a specific chassis frame for the 4WD models.
Today there is growing interest in these unique NAPCO trucks, with several websites dedicated to finding and restoring vehicles and increasing the historical knowledge base.
These include Joe Fox’s Classic GM Truck Site and the Napco Owners Group www.napco4x4.org which have done extensive research on this rare breed and from which Truck Jungle sourced some useful background info for this story. If any of these great US trucks have ended up in Australia, we’d sure like to know about them.
To provide some valuable insight into what the NAPCO-equipped trucks were capable of, take a look at this corporate promotional film made by Chevrolet back in 1957, called ‘Meeting the Challenge’. It is a worthy title, too, because Climbing Colorado’s towering Pikes Peak the hard way – straight up – was certainly a challenge! TJ