I've never seen the word founts used in this sense, only this:
In any case, Australia used mostly American spelling for a century and
more, e.g. this newspaper item from 1916:
On Saturday, 12 May 2018 09:55:59 UTC+10, Andrew Cook wrote:
> 'Fonts' is the Americanisation of the English spelling of the word
> 'founts'. The numerals on tramcars varied from system to system. I assume
> the numerals in the earlier days were painted on by sign-writers, who
> followed a particular style used by the system concerned. I don't think the
> numerals painted on trams were based entirely on actual typographical
> founts. The stick-on numerals on Australian trams today are probably
> typographical, and I think the former MET used Helvetica Extra Bold
> numerals on its trams at a guess. Sans serif anyway!
> Andrew Cook (a former hand compositor).
> *Sent:* Friday, 11 May 2018 5:28 PM
> *Subject:* [TramsDownUnder] Tram number fonts [Was: WANTED]
> Hi Dean,
> I'll be at the Adelaide Museum in late May and can probably help, but I
> think you need to be a bit more specific.
> If you want the details of the font for a tram system, you need to
> specify which era - and sometimes which trams.
> Here's today's pic of a "Sydney 8" ... amongst other numbers.
> Mal Rowe
> On 8/05/2018 8:09 PM, Tram Gunzle wrote:
> > someone with:
> > - a digital camera of at least 10MP
> > - steady hands
> > - a measuring tape
> > - access to STM
> > - time to take detail photos and email them
> > Also, ditto for Adelaide trams with 7, 8, or 9 in their fleet number.
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