TCI For GM Chevy Small and Big Block SFI Flexplate with 10.75" and 11.5" Conv. SFI 29.1 approved. Fits Small and Big Block For Chevy internally Balanced V8 engines using a 6 bolt crankshaft flange. Drilled for 10.75" small For GM converter bolt pattern and also 11.5" big For GM converter bolt pattern.