So i hear that the nissan skyline gtr r34 is illegal in america. is this permanant?

the R34 has always been my favorite car and i hope to buy one someday. ive heard there are special rules you must follow and ive also heard if the car is 20 or 25 years old, i dont remember when exactly, that it will then be ok. can somebody tell me what the rules are? i cant buy one any time soon but its my favorite car and would love to buy one someday.