Here's a quick list of makers and numbers as someone asked me months ago for a part number but only now have found it.

LS400 1990-1994.

EIBACH----------------EIB-8225.140
INTRAX-------------- INX751071
H&R--------------------52425
K-SPORT--------------CLX140-KP (Coilovers)
TANABE-------------- DF210


Japanese Options.
JUN-------------------D-SP (Coilovers)
TEIN------------------ COMFORT SPORT(coilovers)
ADVOC--------------- Tom's Racing (coilovers)
KONI ----------------- scherzen(coilovers)
JIC-------------------- VIP (Coilovers)
JIC--------------------- X-MAGIC (Lowering springs only)
ESPELLIR-------------- EST-073 (Lowering springs only)
RSR-------------------- Ti2000 (Lowering Springs only)
BUDDY CLUB---------- SEDAN SPEC DAMPER(Coilovers)
GREDDY--------------- TYG033 ??Maybe (Lowering springs only)
ZOOM------------------ (Lowerings springs only)

Most of the Japanese can be bought from two firms which will send to the UK, They are RHD Japan and nengun.