2X4 OR 2X3

I AM GOING TO THE LOCAL IRON DISTRIBUTOR TOMORROW TO PICK UP TWO 20 FT. STICKS AND WAS WONDERING IF 2X3 3/16 WALL BOX TUBING BE SUFFICIENT FOR A BODY DROP OR 2X4 3/16 BE BETTER...THE LATTER IS OBVIOUSLY WEIGHS MORE...2X3 IS CHEAPER THOUGH...WHAT'S YOUR TAKE????????????????