At first glance, the Willys MB and Ford GPW look identical in appearance, but with closer observation, hundreds of differences can be found.  This page will point out the major and most obvious differences only.  The purpose of page is to aid you in determining which model W.W.II jeep you have.
    It is important to know that the parts used on Willys MB and Ford GPW jeeps are completely interchangeable mechanically.  When your jeep left the factory it was either 100% Willys or 100% Ford, but from that moment on, motor pool mechanics, government rebuild depots and civilian owners have been swapping parts without regard to whether the part is a Willys or a Ford part.   This means that the jeep you have is likely a combination of the two types.  Often jeep owners will refer to their vehicle as a "GPW with an MB motor" for example.
    What this means is that in order to accurately identify your vehicle, you need to look at many clues.  Generally the vehicle is divided into three major components: the chassis, the engine and the body (also referred to as the "tub" on jeeps). Ideally, you will find that your jeep will have matching  engine,  frame and tub. This is often not the case.  The sections that follow will help you determine the manufacturer of your engine, frame, and tub.

Engine Block
    This one is easy.  Examine the serial number stamped on the engine (see serial number page for location).  The number prefix will tell you the manufacturer.  Willys engines have numbers that start with the letters "MB"  (MB123456) whereas Ford engine numbers usually start with "GPW" (GPW123456)
    If your serial number is not located as shown on the serial number page, then you probably have a post-war  replacement or civilian engine block in your jeep.

Frame
     The easiest way to distinguish between the two frame types is to inspect the front frame crossmember that is beneath the radiator.  The Ford GPW frame uses an inverted "U" shaped steel member here. It is open on the bottom.  The Willys MB frame has a steel tube or pipe type member in this location.
    Another detail to check  is the machine gun mount. In the center of either frame, mounted to a crossmember behind the transmission, is a large, roughly circular plate with four  holes drilled in it .  This is the machine gun pedestal mount.  Only W.W.II jeeps have this feature, and all W.W.II MB/GPW jeeps were equipped with this plate.  The plate differs in design between Ford and Willys  and can be used to identify the frame if the front crossmember is missing.

Body or "Tub"
    This is a more complex determination owing to the variations in bodies used throughout the war. Before  late 1943 Willys and Ford used separately manufactured bodies.  Starting in early 1944 one manufacturer (American Central Manufacturing Co.) began building bodies for both Ford and Willys.  These bodies are referred to as "composite" bodies because they have characteristics of the earlier Ford and Willys bodies combined into one body type. It is recommended that you consult a reference book  (see the How to Get Started page)  to pinpoint exactly which body type you have.
    It is possible to identify certain body characteristics that are associated with either Willys or Ford however.  Starting at the rear of the vehicle: The early jeeps had the manufacturers name stamped into the left side of the rear panel, either a script "Ford" or a block letter "Willys". This practice was discontinued early in the war (by mid 1942).
    Moving  forward to the rear wheel well toolboxes: Ford bodies have a rectangular depression  where the toolbox lock button is installed, Willys have a circular depression here. (note: composite bodies have a circular depression also)  Another toolbox difference was in the toolbox lids or covers.  The Willys MB uses a plain flat cover whereas the Ford has an embossed lid.
    One more significant detail are the toeboard gussets.  These can be viewed under the hood.  They are the roughly triangular braces that extend from the firewall down to the frame.  Ford style gussets have rounded corners and have 3 large holes in each. (note: these style gussets are also used on composite bodies)  Willys toeboard gussets are very angular and flat-sided with five holes in each.
    If your body has round toolbox lock button depressions (like a Willys) AND it has rounded, three-holed toeboard gussets (like a Ford) then your body is probably a composite type as described above.  A composite body installed by Ford on a GPW would have Ford type bolt-on items attached to it (embossed tool box lids, for example) whereas a composite body installed by Willys on an MB would have Willys type bolt-on items attached to it (plain toolbox lid, for example).