CREATE TABLE table_54317 ("PRR Class" TEXT, "Builderpars_m_singles Model" TEXT, "Build date" TEXT, "Total produced" FLOAT, "Wheel arrangement" TEXT, "Service" TEXT, "Power output" TEXT)

What is the build date of the model with a PRR Class of brs24?
SELECT "Build date" FROM table_54317 WHERE "PRR Class" = 'brs24'
SELECT "Build date" FROM "table_54317" WHERE "PRR Class" = 'brs24'