It's just the 1996 model from Gran Turismo 1, with 5-spoke wheels.
Note: The Viper RT/10 in the final GT2 is a 1999 model, hence why it has the same hood vents as the GTS. The GTS originally was faster than the RT/10 when it came out, but Dodge later on altered the RT/10 so it could have similar performance figures to its coupe counterpart.
Ok and yeah, I prefer the 1996 model over the 1999 cause I do not like those 99 viper wheels, so ugly. Its annoying that there isn't a rt/10 with no hood vents in gt2....... besides early screenshots.
I'm a fan of the viper so much that I'm building a 1/25 dodge viper gts-r lm editiin road car model........ and yes its mid-engine!
EDIT:
now I can take any car from drab to fab!
Mod update: Now can make custom rims with dish/lip! The porsche 911 wheels came from NFS: high stakes!
EDIT: again: actually I'm an dingle berry, lol, the rt/10 viper without vents does exist in game! Found it with gts coupe wheels!
So we can have a combo of year gen rt/10 vipers...... (if modded right)
1st: 1992-1993 3 spoke wheels no vents in hood, soft top only, snap on windows only, no a/c, heavier slower engine.
2nd: 1994-1995 gts coupe 5 spoke wheels, no vents in hood, hard top available, a/c available, and wind up windows available, and a upgraded engine
3rd: 1996-1998 gts coupe 5 spoke, vents in hood, gts coupe engine
4th: 1999-(2000) new ugly 5 wide spoke wheels, vented hood, upgraded gts coupe engine, and also abs brakes
So the one I found is a 94/95 viper rt/10, being that it has gts coupe wheels and no vents in hood.