Back when Audi was racing it's R8 LMP at Le Mans, they had designed the car so all parts were easily replaceable. If anything in the back end of the car went bad, they could change the whole rear section in less then four minutes. That meant everything from the engine back. All the brakes hoses were quick disconnect and pre-bled. One year I watched them when they they did it to two cars...one had a gearbox problem, and the other had a bad shock! Yes, it was faster to change the whole rear of the car then change one shock. Engineering at it's finest.
Needless to say, the rules were changed so now you have to finish the race with the same gearbox housing you started with.