the 4 doors are pretty muchthe same as the two doors, inthat there are r32 and 33 gts4 varients. they would have orignally come with the non turbo rb25de in the r33 and i would hazard a guess at the rb20de in the r32. lots of people fit the rb25det...or if they want to go the whole hog an rb26dett. the one you mention withan rb25dett will have had an after market twin turbo manifold fitted to run two turbos onthe rb25.....quite a rare find in itself.
if you find one with the rb26dett in it (r33) and it appears original then buy it cos its one of the few autech/nismo verions of whihc very few were made. (essentially a 4 door gtr)