Me, Tony D, Ian, Erik Messley, and Bryan Lampe have all looked at hundreds of S30 Halfshafts over the decades and never found a length difference. Yes, the left Halfshaft in a R200 install has to shorten noticeably more because of the asymmetry of the R200, but at a stock ride height 280Z it's not an issue. It can become an issue in a lowered 240z and I wrote up something about it 8 or 9 years ago.