if you want to take Wiki's word for it:
"...The standard skid plate was also revised for 2003 to make room for the Rubicon's bigger NV241OR transfer case. The change from the 30/32RH to the 42RLE also gained an additional skid plate.
The Wrangler Rubicon (named for the famed Rubicon Trail in the Sierra Nevada Mountains) was introduced in 2003. It featured front and rear Dana 44 axles with built-in air-actuated locking differentials, 4:1 low-range NV241OR transfer case, 4.10:1 differential gears, 16-inch alloy wheels, and Goodyear MTR P245/75-R16 tires. 2003 to 2004 featured a standard NV3500 five-speed manual transmission, which changed in 2005 to the NSG370, a Mercedes-sourced six-speed. The optional 42RLE four-speed automatic transmission was available from 2003 to 2006.
A limited run of 1,001 Wrangler Rubicon "Tomb Raider" models were produced in 2003 to promote the Tomb Raider sequel, Lara Croft Tomb Raider: The Cradle of Life. Along with the standard Rubicon fare, it also included exterior features such as 16 inch Alcoa forged aluminum wheels, Tomb Raider badging, and Mopar accessories including a light bar, riveted fender flares, tubular grille guard, diamond-plated bumper guard, etc. Interior features included Dark Slate fabric seats with red accent stitching down the center, silver surround instrument panel bezel, red seatbelts and a Tomb Raider badge with serial number. To match the vehicle in the film, it was offered in Bright Silver.
In 2004, Jeep introduced the Wrangler Unlimited with a 10 inch (~25.4 cm) longer wheelbase (LWB), a Dana 44 rear axle with a 3:73 gear ratio and the Command-Trac 231 transfer case; this model is also known by its unofficial designation of LJ. In 2005, Jeep released the Rubicon Unlimited, which has the wheelbase of the Unlimited and the off-road features of the Rubicon such as front and rear Dana 44 axles with locking differentials, diamond plate rocker guards, an NVG241OR transfer case with a 4.0:1 low range, 245/75R16 Goodyear MT/R tires, a six-speed manual transmission and other comfort and convenience options not offered on other Wranglers. This model of the Jeep Wrangler has nearly double the towing capacity than its shorter wheelbase sibling due to increased wheelbase.
In 2005, Paramount released the movie Sahara which featured a Jeep Wrangler. As a way to build off the success of the movie, Jeep released a limited production “Sahara Edition” Unlimited Rubicon.[2] Only 1000 were produced and each one is numbered. All of them are visually identical, but some were offered in a manual and others an automatic. They are all Light Khaki, Unlimiteds. Trim differences over the standard Rubicon include chrome grill, color matched flares, khaki hard top or soft top as well as optional dual khaki tops, Graphite Moab wheels, a Sahara spare tire cover, upgraded two tone premium seats, Sahara decals, tail light guards, and a numbered dash badge.
The 2007 model year brought the complete redesign of the Jeep Wrangler, in both two and four-door models. The TJ platform was replaced by a new JK platform. This next-generation Wrangler was significantly larger than the existing model, with a 2 inch (50.8 mm) longer wheelbase and 3.4 inch (86.4 mm) wider track, though the two door model is actually 2.5 inches (64 mm) shorter in the overall length than the TJ, allowing for better approach and departure angles. With a larger available standard tire size of 32 in, breakover angle is unchanged.
JK was introduced at the 2006 North American International Auto Show with past Chrysler group CEO Tom LaSorda driving one up some steps and through a plate glass window, just as Robert Lutz had done at the show in 1992 with the Jeep Grand Cherokee. The JK was first available for purchase with the 2007 model year.
2007 Jeep Wrangler Unlimited hard top
The JK Wrangler is offered in two versions:
A short-wheelbase 2-door, in X, Sahara and Rubicon trim levels.
A long-wheelbase Unlimited 4-door, also in X, Sahara and Rubicon trim levels.
The Wrangler X is available with factory installed right-hand drive. This model is targeted at mail carriers. Rural mail boxes in the United States are on the right-hand side of the road, and are serviced with the carrier behind the wheel. This may also be useful for carriers who wish to get out of their vehicle without the risk of getting hit by traffic. For the 2007 and 2008 model years, the short-wheelbase Wrangler was the right-hand drive Jeep. For the 2009 model year, the right-hand drive Wrangler will be replaced by the right-hand drive Wrangler Unlimited.
A 3.8 L EGH V6 with a displacement of 230.5 cubic inches (3778 cc)[3] producing 205 hp (153 kW) and 240 ft·lbf (325 N·m) is the base engine, replacing the venerable AMC 242 straight-6. The 2.8 L VM Motori turbodiesel straight-4 producing 174 hp (130 kW) and 302 ft·lbf (410 N·m) used in the Liberty is offered as options outside of U.S, as it does not satisfy U.S. emission control standards for 2007.
A six-speed manual transmission is standard, with a four-speed automatic transmission offered as an option. The lower two levels have the Jeep Command-Trac NV241 part-time two-speed transfer case with an optional Trac-Loc limited-slip differential, while the Rubicon uses a Rock-Trac version of the NV241 with a 4:1 low range. Electronic locking front- and rear-axles called Tru-loc are also standard on Rubicon models. (rear locker optional on X models)
Stability control is a new safety feature for the JK Wrangler. All versions offer off-road tuned Anti-lock braking system and traction control system with electronic limited slip differential. Standard on the Rubicon trim is a new electronic sway bar disconnect system."
Mike