Ok.... I was just checking on the coloured wheels for HZ SL/E and noticed something interesting for the black sports wheels.......

Two black sports wheels are listed in the HZ parts catalogue.....

Part number 2817164 ....... use prior to ADR25A .... superceded by 92003716BA
Part number 92003716BA... use with ADR25A

HQ to HZ are the same part number of 2817164..... prior to ADR25A

ADR25A anti-theft locks first applied from 1st Jan 1978.

So..... the 5mm sports steering wheel was used until the end of 1977 with the 3mm wheel being used from 1st Jan 78..... the same time the ignition lock ASM changed.