After discussing it with one of the site administrators, I've taken the historical information, documents, and photos recently assembled in the Warn M2 Hubs thread and reorganized these in a new thread showing them in a more chronological order. For those who followed the former thread, some of the content in this thread will be familiar (though not all, as much has since been added). As the facts have become clearer, I've continued to update the information below accordingly. Thanks to everyone who participated in the initial discussion! The "Standard" Warn Hub Caps were Warn's initial entry into the field of vehicle hubs, before it began to develop locking models. After WWII in the mid to late 1940's, the public purchased thousands of ex-military Willys MBs and Ford GPWs, as well as Willys' new CJ2a. In 1948, Arthur Warn, then a Willys-Overland dealer in Seattle, Washington, founded Warn Manufacturing and marketed the first free-wheel Warn Hub Caps. Warn Motors circa 1948: This was posted by Dave Eilers on eWillys: "There was some early resistance to using the first generation of the Warn hubs, because jeep owners felt they’d purchased their jeeps for the four wheel drive capability. The initial hubs turned the jeeps into two wheel drive, which some owners felt defeated the whole point of owning a jeep. However, through education and marketing, the Warn folks slowly turned naysayers into advocates." From a 1995 Field & Stream magazine article: The Warn Hub Caps, or Standard Hubs, also became known as "Summer Hubs" since that's when they were typically used, as they effectively converted a vehicle from 4WD to 2WD. Warn made two versions of the Standard Hubs - the earlier "hatched" pattern, below at left, and the later "dimpled" pattern at right: The Standard "Summer Hubs" came in a metal case with instructions (below at left), which also served as a container for the removed parts. When installed, the hubs' integral needle bearings ran around inner race sleeves (at right) that were placed over the axle splines: Initially, Arthur made door to door sales of his hub caps in Seattle, but his wife Sadie saw a larger market and placed ads in Popular Mechanics (below at top left), which started their mail order business. With orders coming in, to meet the increasing demand Arthur began working with Belleview Manufacturing in Portland, Oregon, a small four man operation working out of a two car garage. As the Jeep line quickly evolved, the market for Warn Hub Caps continued to grow. Some of Warn's early advertising: In addition to direct mail order, Warn soon began to sell their hubs through dealerships and retailers as well. Below is an interesting testimonial for Warn Hub Caps from the early 1950's that Warn mailed to prospective customers and resellers. A larger, more easily readable copy can be viewed at More Unique Warn Brochures. (From Yyz's collection, linked to on the CJ2A page): The flyer below, dating from the late spring or early summer of 1953, encouraged resellers to stock Warn hubs rather than competitors' models. It emphasized the expansion of Warn's scope of advertising to include ten different magazines. In this flyer Warn introduced two newly developed hubs, the Model WL-2 manual locking hub and the Model WA-1 "Automatic" locking hub. Note the wide variation in list prices between the three available hub models. (Also from Yyz's collection): The initial WL-2 manual locking hub is often referred to as the Warn "5-ring" hub, due to the five black-painted recessed rings in its aluminum body. These hubs required exiting the vehicle to manually adjust them from 2WD to 4WD or vice-versa. The earliest version of the 5-ring manual locking hubs had an interesting difference from Warn's later designs. David Hoelzeman, the owner of a set of these rare hubs, noted in the Old Willys Forum that the dial of this first early model had to be rotated a full 360 degrees in order to lock or unlock them, and there was only a single red dial alignment 'dot' on the cap. On the later versions of the Warn 5-ring locking hubs, the dial rotated only 300 degrees, and there were two red alignment dots on the cap, one for 'lock' and one for 'free'. This change allowed the driver to tell which mode the hub was in at a glance. Shown below at top is a circa 1953 'one dot' 5-ring Model WL-2 manual locking hub, with cap to body screws and a 'tailed' indicator arrow (photos courtesy of David Hoelzeman); at bottom left, a circa 1956 to 1958 'two dot' 5-ring WL-2, with cap to body screws and a 'tail-less' indicator arrow (photo courtesy of Bruce Mullen); and at bottom right, a mid-1960's 'two dot' version, with no cap to body screws, a 'tail-less' indicator arrow, slightly smaller lettering and differently shaped finger grooves on the dial, and no alignment dot lettering for "Lock" or "Free" embossed into the cap (photo by G. Gordon): Courtesy of Dave Eilers from eWillys, here's a rare mid-1950's installation guide and owner's manual for the 5-ring Model WL-2 locking hubs (images cut & pasted for readability). This manual is for the"middle" (circa 1956 to 1958) version of the 5-ring locking hub: The Model WA-1 "Automatic" hub was the first production Warn hub to allow shifting in forward gears from 2WD to 4WD configuration, and back again, automatically, without the driver needing to exit the vehicle. However, they had to be manually locked in order to operate in 4WD reverse gear. By early 1955, Warn hubs for Jeeps were sold "exclusively by Willys dealers worldwide". These two ads (from eWillys) published that year describe the virtues of the Automatic Hubs: The following pages from an early- to mid-1950s Willys mechandising document (courtesy of Dave Eilers) detail the functioning of the WA-1 Automatic Hub and the WL-2 Manual Locking Hub. As shown below, the earliest version of the Automatic hub had a single dial alignment 'dot', cap to body screws, and a 'tailed' indicator arrow: The Model WL-2 manual locking hub shown is the earlier 5-ring type, likewise with a single alignment dot, cap to body screws, and 'tailed' arrow: This 1955 Willys brochure, again from eWillys, differentiates the the Automatic Model WA-1 hub from the 5-ring manual locking Model WL-2 hub (oddly described here as "Semi-automatic"): These pages from a 1955 Warn Hub Service & Repair Manual (from eWillys) show cutaway and disassembled views of the body and cap of the Automatic WA-1 hub and the manual WL-2 "5-ring" designs. (Note: A complete copy of the 1956 version of this manual can be downloaded here: 1956 Warn Hub Service & Repair Manual) As the Automatic hubs were nearly twice as expensive as the manual locking hubs, they likely also generated greater profit margin for the company. Most of Warn's advertising during the mid-'50's focused on their Automatic hubs, and in turn, the later "Lock-O-Matic" hubs. This ad from 1955 features the WA-1 Automatic hub, which Jeep deemed "Approved Equipment" shortly after its introduction: A set of the later 'two-dot' version of the Warn Automatic hubs, likely dating from late 1955 or very early '56, with cap to body screws and 'tail-less' indicator arrows, is pictured below (photos courtesy of owner Bruce Mullen). As Bruce noted, these hubs are marked left and right, and the indents and lettering were painted red. He further pointed out that these hubs have no internal springs, and that the rear is different from that of later Warn hubs. This Warn flyer from early 1956 advertises the 5-ring 'two-dot' Model WL-2 manual locking hub along with the newly developed Lock-O-Matic Model WO-1 hub, which replaced the Automatic Model WA-1. Though the Lock-O-Matic was similar in appearance to the 'two-dot' Automatic hub, the Lock-O-Matic would engage in 4WD in both forward and reverse gears without the driver having to turn the dial to "lock", and there was no differentiation between left and right hubs. The earliest version of the Lock-O-Matic hub had cap to body screws and a 'tail-less' indicator arrow, as shown below. Note #7 above indicating a "steel hub body" on the WL-2 manual locking hub is in error, as in reality they were aluminum alloy. The WO-1 Lock-O-Matic hub did however have a steel body. An exploded view diagram from 1956 indicating the material specs for both hub designs is below.