Hey man, you might want to check this guy out on Ebay:
http://cgi6.ebay.com/ebaymotor...ws=50
He's in Japan and just wrecked his R32 Skyline GTS-4 (RB20DET), and is parting everything out. I don't think he's auctioned off the flywheel yet, and he said to e-mail him and ask if there's something you wanna buy that he hasn't put up for sale. Ask him if he'll sell you his flywheel!
I think the GTS-4 flywheel should be the same as the regular RWD GTS-t flywheel, can anyone confirm or deny?