I posted on a while back asking if anybody knew of a wiper arm from a later model Mazda that would fit to get rid of the early type round post mount.
Anyhow nobody that I know of knew anything so I spent some time down at the wreckers and scored some Mazda 121 arms that have the more modern type "U" mounting for the wiper blade and although a little bit longer in the reach they go straight on to the spline and work fine.
Will post some pic's up when I have some.

Hope this helps.