CREATE TABLE table_73492 ("Outcome" TEXT, "Year" FLOAT, "Championship" TEXT, "Surface" TEXT, "Opponent in the final" TEXT, "Score in the final" TEXT)

Name the year for clay for boston and guillermo vilas
SELECT "Year" FROM table_73492 WHERE "Surface" = 'Clay' AND "Championship" = 'Boston' AND "Opponent in the final" = 'Guillermo Vilas'
SELECT "Year" FROM "table_73492" WHERE "Championship" = 'Boston' AND "Opponent in the final" = 'Guillermo Vilas' AND "Surface" = 'Clay'