OK, not easy to find. See if an irrigation supply house (like Ewing) can order one for you.
Sorry for the obtuse answers, but we often have questions that remind me of the fella who wanted to use an elephant gun to kill a fly, so our attempt is to steer them toward a fly swatter. Everybody wins, except the fly.
Sorry if I made that assumption.
Still might be easier to buy a smaller lawn tractor for the smaller areas.
Jeff