NISMO - there were several (total unknown - but at least 5) RB versions sold with special Nismo ID plates.
They sported many of the Nismo rally options (suspension, diffs, seats, roll cage, foot rests, etc),
and were probably built as promo cars, and then eventually sold to private buyers in the mid-late 90s.

GROUP A - The Group-A Rally Car was not sold in showrooms (used for the WRC by NME as their Works car).

Misnomers:

"DAKAR" - The name Dakar is sometimes used (mainly in UK) in reference to the RB,
but that name DOES NOT appear in any official texts or anywhere on the cars,
and the car was never entered in the famous rally by that name.
IF ANYONE CAN PROVIDE ANY INFO/EVIDENCE TO PROVE OTHERWISE PLEASE LET US KNOW.

"HKS" - Contrary to some links on the internet - there was NEVER an HKS version or HKS promo car.

THE DIFFERENCES IN THE "RA"
Basically, there were 2 main series/versions/phases of RA cars,
they can be identified by their chassis numbers:
BELOW RNN14-100000 (Early / Phase1)
ABOVE RNN14-100000 (Late / Phase2)

There are actually 4 variations (at each 50000 chassis interval),
but the exact details of the changes are unclear and the 2 middle ones seem to be cross-over periods with bits from both:
000001 (02/90-09/91)
050001 (10/91-07/92)
100001 (08/92-07/93)
150001 (08/93-08/94)

These are the changes made to the Late (above RNN14-100000) models:

- body colour: super white [531] replaced the early ivory/marble white [KJ7]
- body colour: no longer available in grey [TJ1] or red [AJ4]
- umbrella holder: removed and replaced with a blank panel (not the vent from the RB model)
- headrests: changed to solid (from hollow/donut-style)
- interior fabric trim: changed to the same as the SSS & GTI models (no longer specific for GTI-R)
- badge on front grill: changed to "Nissan" (from the "P" logo)
- steering wheel: changed to generic black Nissan logo debossed (instead of red GTI-R logo button)
- windscreen: changed to monotone (no more upper blue section)
- roof lining: changed to vinyl from twill (except for those that chose the sunroof option)
- main instrument cluster: ogos changed to hidden unless lit, and ANTI-LOCK logo changed to ABS
- the water pump: model was changed
- support brackets: a couple were added (clutch pedal bracket and side door intrusion beams)

There were NO changes to the engine or exterior.|

There WAS a limited run of Turquoise Metallic [DL2] coloured examples.
The unconfirmed rumour is that it was for a commemorative event in Japan (possibly Emperor's Day)
Also unconfirmed is the amount, could be anywhere from 20 to 100 - there has never been any proof.
Although it is clear that they are by far the rarest of all the colours...

THE DIFFERENCES IN THE "RB"
The RB (homologation) model was specifically built to be used for Group N rallying, and had all the luxury trimmings removed as standard.
Originally thought to be the difinitive spec - it is now clear that some of the luxury items were available as an option
(but mainly found in the later years):
- no colour-coded side mirrors (grey plastic - standard)
- no umbrella holder (a vent is there instead - standard)
- close ratio gearbox (standard)
- front lsd (standard, but other front diffs optional)
- steel wheels (standard)
- no rear wiper (optional)
- no air con (optional)
- no electric windows or mirrors (optional)
- interior from base-model pulsar (vinyl trim, basic seats, rubber gearstick boot - standard)
- exterior paint marble/ivory white (optional - but it seems most of the early ones are this colour)

There were also many Nismo Rally Options (as seen in the Best Motoring Special #13 video)
[see list below]

Nismo had several RB promo versions sporting all the Nismo options (see Gallery).
Autech sold some of the RB versions (Autech is a Nissan-subsiduary tuning company that sell complete upgraded cars).

THE OPTIONS
There were many factory options available throughout production:
- climate control (common)
- wind deflectors (common)
- plastic protectors (doors, handles, bumpers)
- heated seats (very rare)
- heated mirrors (rare)
- illuminated ignition ring
- rear parcel shelf speaker upgrade

There were also motorsport options:
- rear roll bar
- driving lights
- knee rests
- bumper protector
- foot rests (different from Nismo ones)
- strut braces (different from Nismo ones)
- rear diff cover (different from Nismo ones)

There were also many Nismo options:
- strut braces
- suspension
- clutches
- bushes
- steering wheel
- seats & belts
- underbody guards
- diffs
- etc

NOTE ON NORMAL FACTORY OPTIONS:
It seems that many late models have more of these options than early models, which logic suggests is most likely due to the general rule that towards the end of production showrooms would do good deals on them.

FACTORY COLOUR CODES:
KH3 = Super Black (entire production)
AJ4 = Red (early models only)
TJ1 = Blue-Grey Graphite Pearl (early models only)
KJ7 = Ivory/Marble White (early models only)
531 = Super White (late models only)
DL2 = Turqoise Metallic (special commemorative only) [previously thought to be FM0]

THE OZ RECORDS
Power Output: 270kw (~360hp) at the wheels [two different dynos] [all mods done in Oz]
0-400m: 11.4sec @ 198kph (~123mph) [full street trim] [imperfect launch]
STANDARD RNN14 SPECIFICATIONS
Length: 3975mm
Width: 1690mm
Height: 1410mm
Wheelbase: 2430mm
Tread Front / Rear: 1440mm / 1415mm
Ground Clearance: 150mm
Kerb Weight: RA: 1220kg [RB: 1190kg]
Fully Laden: RA: 1495kg [RB: 1465kg]
Seating Capacity: 5
Turning Circle: 10.4m (5.2m radius)
Drag Coefficient: 0.39
Engine Model: SR20DET (Plasma Version - 54C)
Engine Type: 16 valve DOHC 4 cylinder, with intercooled turbocharger
Displacement: 1998cc
Max Power: 230ps (169kw) / 6400rpm [Euro: 220hp (164kw)]
Max Torque: 29kgm (284Nm) / 4800rpm [Euro: 27.2kgm (267Nm)]
Bore & Stroke: 86 x 86mm
Compression Ratio: 8.3:1
Control System: Electronic Port Injection
Turbo: Garret TB2804 (T3/T25 combination)
Compressor: 60mm, 60trim in .60A/R
Turbine: 53mm, 79trim in .86A/R
Steering: Rack & Pinion with gear sensitive power assist and tilt adjustment.
Suspension - Front: Independent McPherson multi-link strut (hydroscopic and telescopic), coil spring and torsion (sway) bar stabiliser.
Suspension - Rear: Independant strut, parallel link, coil spring and torsion (sway) bar stabiliser.
4WD System: ATTESA - Viscous coupling (front), centre differential and Viscous LSD (rear).
Brake System: 4-sensor, 2-channel electronic ABS.
Brakes - Front: Ventilated Discs
Brakes - Rear: Solid Discs.
Wheels: 14 inch Aluminium 14 x 6JJ
Tires: 195/55R14 82V
Fuel Type: Premium Unleaded Petrol
Fuel Tank Capacity: 50litres
Fuel Consumption:
13.2ltrs/100kms (Urban Cycle)
10.6ltr/100kms (Constant 120kph)
8.1ltrs/100kms (Constant 90kph)
Boot Capacity: 280ltrs
Max Towing Weight: 1560kg
Max Speed: Varies per prochure (223-232kph)
Acceleration 0-100kph: Varies per brochure (5.4-6.4secs)
Acceleration 0-400m: Not defined (Best Motoring Magazine tests have shown mid-high 13s is possible in standard form)
Transmission Type: 5-speed manual
Transmission Gear Ratios:
1st - 3.285
2nd - 1.850
3rd - 1.272
4th - 0.954
5th - 0.740
Reverse - 3.266
Final Drive - 4.125
All information above was taken from the offical Nissan brochures.