So majority of pieces needed to replicate the Nismo ER33 is already made. Huh. I've been under a rock for quite some time, it seems. Oh, and if you still need 400R photos - i've happen to stumble on the service details for that exact (it seems) 400R, with pictures that also showcase the diffuser. I can provide the link here or in the PMs if you'd like to.
Update:
Yeah, KeeJay, Autech made a GT-R 4door for the 40th anniversary of GT-R. I think there were about 447 such cars built.
