I never realised there was 3 series of the standard GTR :S i had a quick look and found this info but that's just different named GTR's Not too sure how reliable this info is either...
1995-1997 (R33)
The R33 was developed in 1995 as a successor to the venerable R32 model that Japan had gotten to know well. The engine in the R33 was nearly identical to the R32. It used the same turbochargers, and the same specification of transmission, although the syncros were made to be stronger. The base model R33 GTR weighs 1750kg.
The R33 GTR launched in January 1995 with the base model GTR and the Vspec model. The Vspec mode weighed 10kg heavier, and had sportier suspension resulting in lower ground clearance. The Vspec also featured the newer Attesa-ETS Pro all wheel drive system, which included an Active Limited Slip differential. The Vspec model also included a four wheel independant channel ABS braking system.
At the same time as the release of the R33 GTR, and GTR Vspec. Nissan released an R33 GT-R Vspec N1 model. Changes on the R33 N1 model are similar to the R32 N1 model. The car was made lighter, by removing the ABS, air conditioning, sound system, rear wiper, and the trunk carpet. The R33 GT-R Vspec N1 received the slightly revised R33 N1 engine.
A special edition R33 was released on November 3rd 1997. The car was called the 400R, with R standing for Racing. Developed with Nismo, it featured an overbored RB26DETT engine, the RBX-GT2, with polished ports, an upgraded exhaust, composite parts, and a more free flowing turbo and intercooler system. The car developed a staggering 450 Horsepower, and allowed the car a top speed of over 200mph.
Info from: http://www.answers.com/topic/nissan-skyline-gt-r
I like how the v spec gets ABS then the v spec n1 gets abs removed. why add it in the first place !