Subaru Impreza Chassis Codes (GD)

[rota wheels wrx]

Here's the short version
GDA is WRX
GDB is STI JDM and EDM
GD7 is STI USDM with 2.5 liter engine

GDB-A first generation bug eye
GDB-B minor facelift bug eye with new grill and large wing
GDB-C minor chassis improvements for bug eye
GDB-D first iteration of the new face
GDB-E major refresh of model with all new rear suspension, 5x114 PCD hubs, wider rear track, underbody diffusers and covers
GDB-F alfa nose

In the manufacturers plate in the engine compartment, there will be a code that states wether it is a GDB and what revison letter

Here is a summary of the changes between revisions stolen from the net
Japanese-spec:

Rev. A (2001): In 2001, the WRX STi received the aforementioned updates. The WRX Type RA STi was produced. The STi wagon was still produced but it's engine only produced 260 PS (191 kW). The STi foglight covers had white STi lettering on them.

The WRX Type RA STi was used for the Group N homologation.

Rev. B (2002): Along with the rest of the Impreza line, the grill and body of the WRX STi was minorly updated by Peter Stevens to give it a more angular look when seen from the side. The foglight covers had pink STi lettering. Not much else besides minor suspension improvements and a small increase in torque output was done.

The WRX Type RA STi was dropped for a new WRX STi Spec C. This model was much lighter than the WRX Type RA as it received lighter glass and body panels. The Spec C's handing was much improved due to an increase in caster (from 3.5 degrees to 5 degrees). This was achieved not by changing the suspension mounting point, but by lenghtening the wheelbase (15 mm). This was done by including different control arms. This increased caster significantly helped the turn-in capabilities of the car. The Spec C also has a steering rack ratio of 13:1. The transmission is supplied with its own oil cooler.

The WRX STi was used for Group N homologation.

The WRX STi wagon had ceased to be produced.

Rev. C (2003): Not much was changed.

The WRX STi was used for Group N homologation.

Rev. D (2004): The WRX STi received the same Peter Stevens-designed facelift that rest of the Imprezas received. The WRX STi is now capable of being ordered with DCCD.

The WRX STi Spec C Type RA was released. It sported a carbon-fiber wing and a carbon fiber lip. It also had a new set of BBS wheels as well as a newly tuned engine.

The WRX STi V-limited was released. It sports 4-way dampers tuned by Subaru World Rally Team's Group N driver Toshi Arai.

The WRX STi was used for Group N homologation.

Rev. E (2005): The WRX STi receives the same increase in wheelbase as the Spec C. All STis received additional rear fender flaring in order to allow an increase in wheel size. The wheel size went from 17" x 7.5" to 17" x 8". In accordance with the increased wheel width, steering lock-to-lock turns have been reduced. Wheel hub strength was improved. The P.C.D. was changed from 5 x 100 to 5 x 114.3.

The DCCD mechanism is improved with the addition of a yaw rate sensor that helps the AWD's computer determine torque distribution to the wheels.

The WRX STi Spec C WR-limited was used for Group N homologation.

Rev. F (2006): The WRX STi continues on relatively the same. The Impreza line's looks have been changed by Andreas Zapatinas.

The WRX STi Spec C's receives the Arai tuned dampers and a 21-mm swaybar. The rear suspension is changed from rubber pushings to pillowball bushings. The strut tower was further stiffened for improved handling and stability. The strut towers were reinforced for better handling and better ride characteristics. The engine mounts were changed from metal to liquid-filled plastic mounts to reduce vibrations into the car's cabin.

The DCCD is updated with the use of a torque-sensing mechanism inside the DCCD. The torque split is changed to 41/59.

The WRX STi Spec C was used for Group N homologation.