The only 1 x 300zx turbo auto is def a Z31 -which afaik is correct
Also 300zx 2+2 are also def Z31
If you click on each one , there is a splilt with year of reg and 2+2 license from 1984, whereas just 300zx are from 1990
Dunno -but there's a thumping 29pages worth from A-Z of "missing"