2000 V6 Mustang has had three starter failures

My 2000 Mustang V6 has gone through 3 starter motors (remanufacturered ones by Superior) in the past two years (70,000-84,000 miles). Each time, the same situation: turn the key: no clicking -- or any other --sound; no drop in brightness of headlights or gauges. The starter just ceases to work. The place that installs it always honors the warranty for the starter, but charges $116 for the installation labor, plus I have to pay for most of the towing. I'm afraid to drive this any distance, for fear of getting stuck. I'm thinking that the aftermarket Interstate battery may not have high enough cranking voltage so that cranking amps increase as a result and slowly fry the starter. Have other 2000 Mustag V6 owners had the same problem? What tests do I need to do to isolate the cause of this problem and fix it? All thoughts are this topic are welcome.