CREATE TABLE table_55506 ("PRR Class" CLOB, "Builderpars_m_singles Model" CLOB, "Build date" CLOB, "Total produced" FLOAT, "Wheel arrangement" CLOB, "Service" CLOB, "Power output" CLOB)

What is the PRR class of the freight train built in 1967 with a b-b wheel arrangement?
SELECT "PRR Class" FROM table_55506 WHERE "Wheel arrangement" = 'b-b' AND "Service" = 'freight' AND "Build date" = '1967'
SELECT "PRR Class" FROM "table_55506" WHERE "Build date" = '1967' AND "Service" = 'freight' AND "Wheel arrangement" = 'b-b'