We have an FG84 in at work at the moment with the No-Spin option but it hasn't been driven yet so I can't give any report. If anyone wants pics of the rear LSD diffs let me know. We've still got the original FG84 LSD centre from that truck on the bench and one of the tour operator workshops near home has a FG649 and the older / smaller FG637 LSD centres lying around. No problem.
John.