The factory 5R55S automatic transmission used in the new Ford 3 Valve Mustangs is fairly strong from the factory. However, our R & D engineers discovered several areas which needed improvements to handle the increased horsepower output of modified Mustangs. The TCIš Ford 5R55S Master Overhaul Kit includes additional clutches with exclusive lining, bands with heattreated struts, gaskets, seals, and various upgraded components to prepare your 5R55S transmission for big horsepower and heavy abuse