Hi All:
Well, all pre-1969 Land Cruiser axles have coarse (10) splined axles at the differential. The post-'69 axles are all fine (30) splined at the diff.
All pre-1976 front axles had coarse splines at the lock-out hubs, while the post-'76 have fine (27) splines at the hubs. This change came about at the same time as the switch from front drum brakes to front disc brakes.
Pinion splines were coarse up to and including 1977, while '78 and up are fine splined.
All the above info is for US-market Land Cruisers - other markets may vary.
Longfield CV ("Birfield") joints are all intended for disc brake frontends, and are available either in standard (27) or 30 spline models.
All aftermarket replacement diff gear sets have fine-spline pinions.
Regards,
Alan