These Holley Transmission Installation Kits come complete with everything you need to bolt a TKX or TKO transmission to almost any Gen III, Gen IV, and Gen V Small Block Chevrolet Engines with a 6-bolt or 8-bolt flywheel. Built with a mixture of our best brands including Lakewood and Hays, this kit includes a bellhousing, billet steel flywheel, clutch and pressure plate, hydraulic release bearing, roller pilot bearing, and all hardware needed to install these components. The 319-504 is set up to be used with the 6-bolt flywheel LS engines which are the majority of the Gen III and Gen IV engines produced before 2009 (LS1, LS2, LS3, LS6, LS7, LM7, LQ9, L33, and similar truck engines). The 319-505 is very similar to the 319-504 but is designed to be used with the 8-bolt flywheel LS and Gen V LT engines that come after 2009 (LSA, LT1, LT4, L83, and similar truck engines).