The 8,500 lb Advanced Single Pulley Gear Plate Assembly features a solid aluminum worm housing, extended support blocks, easy to reach grease fittings, and composite bronze backplate bearing. No steel on steel moving parts. The 8,500 lb plate has a single worm gear with a hardened steel worm and solid bronze 96 tooth worm gear. Rated for 8,500 lb capacity. Gear plate assembly only.