Ballasts rhymes with:
analysts, anti-federalists, capitalists, catalysts, finalists, herbalist's, herbalists, herbalists', institutionalists, journalists, nihilists, novelists, socialists, specialists, symbolists, televangelists, traditionalists, ultranationalist's, ultranationalists, violist's, violists
Ballasts sounds like:
ballistic, ballistics, bellsouth's, biologists, blackouts, blackstock, blasts, blockades, blockheads, bulkheads