Each GM division specified its own version of the Turbo 400 and bolt pattern varied with the application. Pontiac shared a bolt pattern with Oldsmobile and Buick (B-O-P), and Cadillac beginning in ’68. Chevrolet used its own. The Pontiac transmission case through the mid ’70s (right) was beefier than its Chevrolet counterpart (left) in most instances. GearStar technican Patrick Walczak states that in his 38 years of building transmissions, he’s rarely seen a case fail, and that includes at the Level 4 capacity of 1,200 hp and 1,000 ft-lb. He does, however, recommend longer locating dowels on the block’s rear flange as well as a transmission blanket or bellhousing shield where racing rules require them.