After some research and cross references, I've ordered a steering boss for '98 F73 that fits perfectly, at a very good price, and good quality. It's said to fit Toyotas (Hilux, Celica, Corona, Corolla) and Daihatsu Sedan (Charmant? Charade?)

Maybe someone will be interested.

Here is a link to the item on ebay:

http://www.ebay.com/itm/161211361106?_trksid=p2059210.m2749.l2648&ssPageName=STRK%3AMEBIDX%3AIT