There are 2 R33 GTR LM Editions built for the 24 Hours of Le Mans Race, but I assume you have found the Street Legal Version, as the 2 Race Versions are sitting in Nissan's warehouse.
For all I know, the R33 GTR LM Edition still ran with the RB26DETT but it was enlarged to a 2.8Lt and had a 6 speed gearbox.
Surprisingly they are RWD.
You will have to get the VIN Numbers and run it through the Nissan FAST System, or post it up in the Nissan FAST Thread and some can decode it for you.
I believe there will be a build plate to say if it is a genuine R33 GTR LM Edition.
In honor of the success of the Skyline at Le Mans, the Street Legal Version I think they only came with a RB26DETT, Nissan marketed a Limited Edition R33 referred to as "LM Limited".
Not many Street Legal Versions were built and were only available in Competition Blue or (maybe) Champion Blue - BT2 (Paint Code) You will probably find this on the Plaque.