326-455 Neutral Balanced SFI Approved 166 Tooth Flexplate- 2.75" center (fits all aftermarket cranks and stock cranks up thru 1974)
Transmission Bolt Patterns Included: TH400, TH350, 700R4
Benefits/Characteristics
To use with cranks with 2.5" hub you can use the Butler spacer ring BPI-1025 and cranks with 2-9/16 hub you can use the BPI-1024 adapter
Internal (Neutral) Balance vs External (Stock) Balance
Pontiac balanced the cranks from the factory using a method called external or stock balance. This called for an offset weighted flexplate or flywheel. Some had holes drilled to lighten one side or an additional weight bolted to it in order to add weight to a side. Butler and most shop now internally or neutrally balance crankshafts. This means you can use a flexplate or flywheel that is neutrally balanced with no offset holes or added weights.