Unsure what a “floor” harness is but have replaced the engine harness on a 2003. Engine harness is a pain with the engine in the vehicle. Easier completed with engine pulled. Lots of ground and other wiring on the back of the heads, intake and block. Plus the transmission harness is part of the engine harness at the back of the motor. I am guessing the flat rate book time for this task is rather high. Download a factory service manual online and review the factory instructions. I did this for mine and alleviated a lot of pain and suffering. Good luck!