The JW Performance Ultra Bell are SFI 30.1 Certified. Allows for use of all 6 bellhousing bolt locations on GM LS engine blocks. Also works with Standard Big and Small Block Chevrolet and BPO Applications. Works with OEM TH400 and TH350 Cases. These bellhousing are make of T6 Cast Aluminum and precision machined in the USA, 5x stronger than OEM bellhousings. Works with most 11 in. and smaller torque converters. Comes with hardware kit. O-Ring seals on bellhousing face prevent leaks. Requires removal of OEM bellhousing on OEM cases. No Dust Shield Provision.