Quote Originally Posted by Innuendo View Post
I wouldn't put too much credence into the manual. The reason for the modification had to do with an Australian Design Rule change.
The 3mm thick steering wheels were fitted way before January '78.
I would. I know quite a few people with original 77 HZ GTS and Sandman that have 5mm thick spokes. HZ manual states 5mm wheel to be fitted to ADR 25 vehicles and 3mm wheels to be fitted to ADR 25a vehicles. ADR 25a became effective as of 1st Jan 1978.

I do concede that the new wheel could have been fitted at some plants prior to this date and some early HZ's could be fitted with the 3mm wheel.