The first 25,808 Willys MBs used a welded steel grille very similar to the Ford GP design, and there were a host of other differences from the later Willys.  These early MBs had "Willys" embossed in the back panel.  In production, the slat grills were given running changes until they finally evolved into the standard 'stamped-grille' MB we know and love.  The slat grills are an uncommon find these days; some sources say that fewer than 25 survive.  Owner Reg Hodgson of Edmonton, Alberta, Canada is the Editor of Army Motors , the official magazine of the Military Vehicle Preservation Association
Willys built two Quads in the competition for a large-scale contract and this is the vehicle that won it.  The Quad's major asset was its 60hp "Go-Devil" engine that literally blew the doors off Bantam and Ford (the other two contenders for the Army contract)  The Quad, however, was a heavyweight and had to go on a big-time diet to meet the Army's requirements: when re-weighed, it was ounces inside of the 2,160 pound limit.  Both Quads have since disappeared, but one lasted long enough to be photographed in the early 1950s.  If Bantam Number One marked the beginning of the Jeep era, the Quad marked the beginning of Willys dominance of the series
The Pygmy was Ford's competitor in the contract race.  Two were built, one by Ford and the other by Budd.  The Ford unit was accepted for testing and was run alongside the Bantam and Willys units.  The Ford's overall layout was highly praised and became the pattern for the later Willys MB.  Like the Bantam, the Pygmy fell victim to the Quad's more powerful engine.  The vehicle in the picture is the actual unit that was tested at Holabird in 1940.  Owned by the Alabama Center of Military History, the Ford is the only remaining survivor of the fierce, three-way competition that marked the opening chapter of the Jeep legend that survives to this day.
Years produced : 1940
No of units : 2
Years produced :1941
No of units : 3700
A direct descendent of the Pygmy, the Ford GP was an undated model produced under an initial contract for 1,500 vehicles from Ford, Willys and Bantam.  As Lend-Lease requirements increased and the Willys design was finalized for mass production, more GPs were ordered, and Ford ended up building 4,456 units, most of which went to Lend-Lease.  Contrary to popular belief, the GP did not stand for "General Purpose".  GP was a Ford engineering term, "G" for Government contract vehicle and "P" for 80 inch wheelbase Reconnaissance Car.  Of the three early Jeep models, Ford has the most remaining specimens: about 200 are known to remain including Steve Greenberg's restored '41 to the left.
Years produced : 1941
No of units : 1553
Willys knew that the Army would want an improved model and started development of the MA even as the Quad was being tested.  In the three-way deal, 1,500 MAs were ordered.  The MA was definitely an evolutionary vehicle.  Very much different than the later MB, the MA featured a column shift and a host of other detailed changes that put it between the Quad and the MB.  The basic drive-train was still the Warner Gear and Spicer components of the Quad, Ford and Bantam.  The MA is the least common of the pre-production Willys, with only about 30 examples knows to exist of the 1,553 originally built; most were sent to Russia under Lend-Lease.  This MA belongs to the Alabama Center of Military History.
Using the term that has become generic in the English language, this is the undisputed first "Jeep".  Built by the American Bantam Car Company of Butler, PA, it was delivered to Camp Holabird, MD on 23-Sep-40.  The first vehicle of a 70 vehicle contract, "Old Number One' was tested thoroughly and then spent the rest of its short life as a demo vehicle.  It was wrecked in a traffic accident early in 1941, sent back to Butler and disassembled.  The mechanical pieces were probably incorporated into the Bantam Mark IIs that were then in production.  Legend has it that the useable body sections were buried along with a pile of scrap on the Bantam grounds (US Army)
Years produced : 1941
No of units : 2605
The BRC-40 was the final evolution of the Bantam design.  The Army initially contracted for 1,500 units, but 2,605 were eventually assembled.  Bantam ceased motor vehicle production after the last was built in December of 1941 and carried on building trailers, torpedo motors and landing gear.  The BRC-40 had many fine features and was well liked by the Allied forces that used it; it's light weight and nimble handling was particularly noteworthy.  At least 100 BRC-40s have survived the years, making them the second most common of the pre-production 1/4 tons.  This restored BRC-40 belongs to Steve Greenberg of Portland, OR 
Years produced :1942-1945
No of units :25808
Years produced :1941-1945
No of units : 281578
Willys recognized the fact early on  that production capability was limited to meet the contract numbers specified.  So Willys sub-contracted with Ford to build the MB under license agreement with Ford Motor Co.  These units built by Ford, known as the GPW for Government, 80 inch wheelbase, were almost identical except for a few distinct differences.  First, most of the bolt heads included a script "F".  Secondly, the tailgate area was embossed with Ford in script.  These were the early models before the government disallowed the practice of free advertising.  This 1944 GPW (s/n 200493 11-May-44) is owned by Herb Tate of Austin TX.
Years produced : 1950-1952
No of units : 45473
Years produced: 1940
No of units : 70
Years produced : 1940
No of units : 2
A direct knockoff of the CJ-3A, the M38 was upgraded for GI use by a stronger frame and suspension, a 24 volt electrical system, and full-floating rear axle, in addition to a multitude of military accoutrements.  These rigs saw combat in Korea, but production was low at 61,423 units.  An export version was built from 1953 to 1955 for foreign military forces.  The headlight guards, blackout lights, battery panel on the cowl and tool notches on the body are the way to ID them.  Some were equipped with Ramsey winches.  Reg Hodgson's M38 (shown here) is decked out in Korean war vintage Canadian colors
This was the first appearance of the 'round-fender' Jeep that would eventually become the CJ5.  The M38A1 was quite different that the CJ5, having a stronger chassis and reversed front spring shackles, in addition to the military accoutrements such as standardized GI instruments and a 24 volt electrical system.  The M38A1 lasted quite awhile in military service.  Even after it was replaced by the high-tech Ford M151, they could be seen in OD green as late as the 1970s.  In all, 101,488 units were produced, some of which went for export.  This rig is owned by George Baxter at Army Jeep Parts in Bristol, PA 

             
Years produced :1952-1957
No of units : 101488
Years produced :1953-1963
No of units : 6500
Although the M170 is often referred to as the "military version of the CJ-6," it would be more correct to call the CJ-6 a civvy M170. As with the M38A1, this new Jeep configuration was developed first for the military. Only about 6,500 four-cylinder M170's were produced over ten years, many outfitted as field ambulances. Others were used by the U.S. Marines as light six-man troop carriers. One unique feature is the mounting of the spare tire inside the body on the passenger side, to allow stretchers to extend over the tailgate where the spare would normally be on a military Jeep. As a result, the unusually large passenger side door opening is partially blocked, particularly when a jerry can is mounted in front of the spare. The driver's side door is the same as an M38A1.
Years produced : 1961-1969
No of units : unknow
This series was developed from the late 1950s to the early 1960s and then built from 1961 to 1969 by Ford and AM General.  This vehicle replaced the M38 and M38A1 with a radically different suspension system consisting of independent front and rear trailing arms compared to live axles.  In addition, the body was significantly redesigned.  These vehicles were reported to have a higher incidence of roll-overs prompting the government to design and install a Roll Over Protection System (ROPS) and seat belts for all units.