The GM Gen III/IV (4.8L through 6.2L engines ... with the spacer is designed for a 300mm (11.8-inch) bolt pattern, while most Gen I transmission torque converters use an 11.7-inch bolt pattern.

GM retroactively called the TH400 ... for use with LS-series engines. The earlier transmissions will have the standard six-bolt pattern used in Chevrolet big- and small-block V8s.

As electric cars become more common, so too is the idea of doing an electric motor swap into a previously internal-combustion car. High-end shops and hobbyists have been at the forefront, but ...

Although the bellhousing bolt pattern is the same for all Buick ... Most standard GM car and pre-1967 truck manual transmissions use the standard GM bellhousing with a retainer bore of 4.686 ...