Brushless power can wreak havoc on plastic slider type driveshafts. You can increase their strength with a wooden dowel rod. Cut to fit the entire length of the inside of the male side of the shaft, leaving a bout a 1/2-inch or so sticking out. Coat the dowel with glue prior to pressing it all the way in to the shaft. You can also check out threaded rod that will actually thread itself into the shaft.
