I'm stumped. I'm trolling for some Previa esoteria regarding cylinder heads.

The OEM parts listing thing that I often use lists three different cylinder head assemblies for a '94 2TZFE (NA engine):
11101-79055
11101-79065 (China Spec)
11101-79095 (California Spec)

Only the last one (CA Spec) is listed for the 2TZFZE

Only the first and second are listed for the '93, and only the first is listed for the '92 and earlier.

Not that I want to spend over a grand for an OEM head - it's easy to get a whole Previa for that - but the "California Spec" head appears to be a sort of phased in change in '94, rather than a sharp NA -> SC change. Does anyone know how the "California Spec" head assembly ( -79095) differs from the earlier one (-79055)?
Is the newer head backward - compatible to the earlier NA engines? If not, why not? Or only to the '94 2TZFE?

Thanks