CREATE TABLE table_18899 ("Rnd" FLOAT, "Circuit" TEXT, "GTO Winning Team" TEXT, "GTU Winning Team" TEXT, "TO Winning Team" TEXT, "TU Winning Team" TEXT, "Results" TEXT)

What was the gtu winning team when the gto winning team was #48 greenwood racing?
SELECT "GTU Winning Team" FROM table_18899 WHERE "GTO Winning Team" = '#48 Greenwood Racing'
SELECT "GTU Winning Team" FROM "table_18899" WHERE "GTO Winning Team" = '#48 Greenwood Racing'