Two seats technically is correct for model number. The Ryan ST-A was built as a tandem two seat trainer aircraft. Somewhere in time the front pit of N17357 was abandoned for this aircraft, rendering it a single seat aircraft. (A Ryan STM version with variations for export did have one seat as a lightweight fighter or advanced trainer). Such changes not always picked up by the FAA data base, which is rife with far worse errors. See N9553 Profile page and NuWaco ATO Taperwing Article here, for example.
