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Understanding Your Jeep's Model Code

Understanding Your Jeep's Model Code

Although Jeeps are a popular civilian vehicle and have been for decades, they were originally used for military purposes. Due to the rich history of both the civilian and military models of these vehicles, they are a beloved collector’s item amongst those who love gathering and restoring classic vehicles. However, since there have been so many different Jeeps over the years, figuring out which one you have can sometimes be difficult. When in doubt, look toward the model code. This guide will help with understanding your Jeep’s model code so you can swiftly identify which Jeep you have on your hands.


To begin, we’ll discuss one of the oldest and most famous Jeeps of all time—the Willys MA. The “MA” is the designation for the pre-standardized Willys-Overland Jeep that immediately followed the original Quad M prototype. The “M” stands for “military contract” and the “A” signifies the model, with this specific model having a production date of 1941. As you’ll see from the list below, that final letter is going to be very useful in figuring out which classic Jeep you’re looking at.


Similar to the Willys MA, the “M” in MB stands for “military contract”, with the B indicating the specific model. This model followed in the footsteps of the MA, with a few notable differences that helped it thrive in WWII. MB’s were in production between 1941 and 1945.


Much like the MB followed in the footsteps of the MA, the GPW was the follow-up to Ford’s GP prototype. The “G” stands for “government contract,” with a common misconception being that “GP” was effectively meant to stand for “Jeep;” however, this isn’t the case. In reality, that “P” doesn’t stand for a particular word. Instead, that “P” signifies the vehicle’s 80-inch wheelbase. The addition of the “W” in the name is due to the licensing of the Willys design and engine when the GPW was swiftly put into production for use in WWII between 1942 and 1945.


Only built between 1942 and 1943, the GPA was the amphibious follow up to the GPW, hence the addition of the “A.” Commonly referred to as the “Seep” (a combination of “sea” and “Jeep”), the GPA was an experiment that didn’t quite work out, which is why production on these vehicles was quickly halted prior to the end of WWII, unlike its predecessor.

MC (M38)

Although this was a post-WWII vehicle, it displays an “M”, once again, for military contract, with “C” indicating the model, which was produced between 1949 and 1952. Although these were not for WWII use, they did aid the United States during the Korean War. This Jeep also carries the moniker M38.

MD (M38A1)

Continuing the trend set forth by previous models, the “M” stands for military contract and the “D” is the model signifier. This Jeep, which began production in 1952, was a direct follow-up to the aforementioned MC, or M38. The most notable difference between this model and its predecessor is the round fenders, which effectively accommodated the new Willys Hurricane engine—a replacement for the iconic Go Devil engine used in many previous Jeep models including the Willys MA. The MD was in production for a significant amount of time, beginning in 1952 and lasting all the way up to 1971. Although this is an impressive production lifespan, the CJ5 was in production for even longer as you’ll learn below.

MDA (M170)

Around 1954, a follow-up to the MD came to fruition in the form of the MDA, otherwise known as the M170. Instead of being specifically built for light reconnaissance purposes, the MDA’s function was to serve as an ambulance. One of the biggest changes between this model and its predecessor is the wheelbase, which extends an extra 20 inches. Instead of the 81-inch wheelbase, the MDA sports a large 101-inch wheelbase.


This Willys-Overland flat-fender came to fruition in 1945 when WWII came to an end. “CJ” stands for “civilian Jeep.” Whereas previous Jeep models were specifically used for military purposes, this model was for use on civilian roads. What makes the 2A at the end of CJ2A so special is that it signifies the first-ever time a Jeep had a 7-slot grille.


In 1949, four years after the CJ2A began production, a new Willys-Overland flat-fender hit the road: the CJ3A. While the CJ3A and the CJ2A are both civilian Jeeps, there are a few key distinctions. The CJ3A displays a one-piece windshield that, unlike its predecessor, does not flip open to allow for ventilation. The CJ3A does have ventilation, but the vent is directly in the middle of the windshield frame in this model. Another factor you can rely on when you have a CJ3A as opposed to previous models is the Dana 44 rear axle.


In 1953, another civilian Jeep hit the streets: the CJ3B. While this Kaiser flat-fender had the same Dana 44 rear axle as its predecessor, there is a very distinct difference between the two. The CJ3B displays a higher hood than the CJ3A to accommodate the vehicle’s new F-head engine, aka the Willys Hurricane engine previously mentioned as part of the MD (M38A1) breakdown.


The CJ5 is a civilian Jeep that first hit U.S. streets in 1955. This Kaiser round-fender had a long production life, which came to an end in 1983. The round design of the vehicle’s fender was another alteration made to better fit the Hurricane engine. With a production life of nearly 30 years, the CJ5 is one of the most popular and beloved classic Jeeps of all time.

Now that you can worry less about understanding your Jeep’s model code, identifying which Jeep you’re looking at should be much easier. If you know which model you have on your hands, this in turn makes finding the right parts for your restoration project much easier as well. If you’re in need of any replacement parts for your classic Jeep, we’re here to help. At Army Jeep Parts, we have a wide range of vintage Jeep parts for nearly all of the vehicles mentioned above, as well as a few, more including but not limited to the M718, M422 Mighty Mite, and M151 Jeeps.

Understanding Your Jeep's Model Code