There was a "DJ" the Dispatch Jeep, the old FSJ, are SJ's, the VJ was the old Jeepster. All vehicles have this sort of model designation, Jeeps are just the only ones that are really all that common outside of the auto industry and people don't think you're crazy. Check out a rice rocket board, they use it for Hondas and what not too.
If you look at an invoice for a jeep it is actually something like KJJ74 The KJ=liberty, the extra J = 4x4 and I don't know what the 74 is. I think it's the trim line. All your options have thier own special codes too.
Here it breaks the VIN down for you. Vin#'s and Model Code are two totally different things.
http://en.wikipedia.org/wiki/VIN#Parts_of_the_VIN
Stole this from another forum - no guarantees on total accuracy, but pretty darn close(it is missing the TJ-L and the XK):
M170 - Similar to a military version of the CJ-6. 4155 of them were made in the mid-50's and early-60's.
CJ - The first civilian version of the military-inspired short-wheelbase Jeep, made '42-'86. Encompasses everything from flat-fenders to Scramblers. Like many other early Jeep designations, "CJ" actually stands for something: Civilian Jeep. Various numbers followed the CJ designation, indicating different body styles within the CJ line:
CJ-2A - A flat-fender, very similar to the military MB ('45-49) except that the headlights bulge out of the grill instead of being inset.
CJ-3A - A flat-fender, very similar to the military M38 ('48-53).
CJ-3B - A flat-fender, the top of its hood sits 4" higher above the fenders than the 3A to clear the new F-head engine ('52-68).
CJ-4 - Only one prototype is known to exist. It was discovered in 1997(?), still in the hands of its second owner. It looks like a 50/50 mix of a CJ-3A and a CJ-5, with only slightly-rounded fenders.
CJ-5 - The civilian version of the M38A1, but with the front shackles under the bumper like most other models. 81" ('55-'71) or 84" ('72-'83) wheelbase. Front fenders are rounded like all subsequent short-wheelbase Jeeps. Easily distinguished from the CJ-7 by a small doorway with a rounded, sloping rear edge.
CJ-6 - Essentially a CJ-5 that was stretched 20" ('58-75), intended for use as a small pickup.
CJ-7 - A compromise between the CJ-5 and CJ-6, having a 93.4" wheelbase (like the YJ and TJ). The body tub is very similar to the YJ and TJ, but the rear wheel wells are round instead of angular. Made '76-'86.
CJ-8 - Also called a "Scrambler." Similar to a CJ-7, but with an extra 10" of wheelbase and an even longer rear overhang. Like the CJ-6, it was intended as a small pickup, but never really found its niche. Only 27,000 were made from '81-'86. Commonly seen with half-cab tops that surround only the front seats.
CJ-10 - A more truck-like Jeep built mainly for export from 1981-85. Easily distinguished by the square headlights in the fenders and the 10-slat grille.
YJ - The original Wrangler, made '87-'95 (though production actually continued into March of '96). Rectangular headlights make it the sensored word child of the of the short-wheelbase line. Rear wheel wells are larger and more angled than the CJ-7, but otherwise the two are visually quite similar.
TJ - The second generation Wrangler, made '97-present (actually began shipping May of '96). Round headlights, coil suspension, and a much more car-like interior distinguish it from the YJ.
SJ - The full-size Cherokee ('74-'83), Wagoneer ('63-'83), Grand Wagoneer ('84-'91), and J-truck ('63-'87). In 1984, Jeep introduced the down-sized XJ and started calling them Cherokees and Wagoneers, leaving only the Grand Wagoneer in the SJ lineup until its demise in '91.
M-715 - A 5/4-ton military pickup built '67-'69. It somewhat resembles a J-truck (SJ), only bigger and badder.
XJ - The down-sized Cherokee ('84-'01) and Wagoneer ('84-'89?). It was (probably?) the first Jeep to use a unibody chassis.
KJ - The Liberty ('02-present), which replaced the XJ in Jeep's product lineup.
ZJ - The Grand Cherokee ('93-'98), which replaced the Grand Wagoneer (SJ) as Jeep's luxury cruiser after a 1-year hiatus. Though much more aerodynamic than the SJ, it's obviously less rounded than its replacement, the WJ.
WJ - As the more bubble-shaped, aerodynamic replacement for the ZJ, it continues the Grand Cherokee name ('99-04).
WK - The third style of Grand Cherokee has a more angular design than the WJ and also joins the Liberty in having an independent front suspension ('05-present).
MJ - The Comanche pickup ('86-'92). It shares much in common with the XJ of that era, including its front unibody chassis. It replaced the full-size Gladiator and J-truck pickups of the SJ era.
DJ-3A - Dispatcher (postal) version of the CJ-3A, made '56-65. Only 2-wheel drive versions were available.
DJ-5 - Dispatcher (postal) version of the CJ-5, made '65-8? by Jeep and then AM General. Only 2-wheel drive versions were available. A DJ-6 (long, like the CJ-6) was also made from '65-68.
VJ - The Jeepster ('48-50) was an attempt by Willys to spice up their vehicle lineup. 2WD, 72hp, and poor marketing doomed it to be discontinued after less than three years.
C-101 - The Jeepster Commando ('66-73) was an attempt by Kaiser to compete with with the Bronco and TLC. The C101 was part CJ and part Wagoneer, advertised as a "happy combo, racy and rugged." This time around it had 4WD, and came in convertibles, hardtop wagons, and half-cab pickups.
FC - Forward Control pickups, with the cab directly above the engine. Made '57-'63
-Marisha
(sorry that post got a little longer then intended...)