I think you had slightly fewer top-load manufacturers than front-load: TL included KitchenAid, GE, D&M, Whirlpool, Frigidaire and Westinghouse. They generally used their usual systems--KA used their single-level wash throughout the life of their TL manufacturing; GE moved from impeller to wash arm with tower, D&M moved from impeller to washarm and used the roto-rack over the fixed douchenozzle, Whirlpool had dual wash arms; IDK about late Frigidaire TL and late Westinghouse TL (don't think there was a spraytube Frigidaire TL; there clearly was an impeller TL Westinghouse (from their built-in line) but IDK when they moved to an arm design and whether they had a second level wash).