To digress a little further from the topic, as many will probably know, RAAF Macchis and other types had a beep transmission setup wired in to the undercarriage system. Turning base, you'd make the appropriate call (e.g. base 3 greens), and the military tower would give landing instructions and say "check wheels", to which you'd respond by pressing the beeper switch.
Later when I was flying the Iroquois, we used to think it was funny on occasion to say "base two skids", or "base, skids down and welded", and push the tone button on the UHF as if we had an undercarriage beeper.