Apologies for the thread Necro, but thank you to Martin Y the OP for this thread, it was exceptionally useful for sorting out my MK1 Eunos speedo misreading by around 10MPH following a swap to a 3.6 final drive.
Just a couple of bits to add, the parts are all still available and are as follows:
1011-17-442A (aluminum sleeve that's offset for the smaller diameter gears) £18-64
9922-20-214 (small roll pin to lock shaft and gear into sleeve) £1-14
9958-60-8166 (internal oil seal for shaft to sleeve) £3-38
1011-17-443 replaces incorrect P/N 1110-17-443 (o-ring to seal sleeve to transmission) £4-47
I hope that makes it even easier for someone else!
BTW the speedo now reads around 2mph under at 70mph which is perfect! 30 is spot on matching the GPS
I am also running a 6 speed gearbox and have filled it with filled with Castrol Syntrans Multivehicle 75W-90, a massive difference to the slickness of gearchanges!