I was driving yesterday pulling a small U-Haul with my 2010 range rover sport. While I was driving about 60 miles an hour I heard a grinding noise for a second been lost all gear power. I was able to pull over and stop all the electric still work as well as mechanical except for when I put it in any gears Only the engine Revs up No motion. I have tried all the gears and get nothing but when I put it back in park there is a grinding noise. Would you think I would need to replace the transmission? Could it be anything else? FYI I had been towing for a couple of days.