B&M Flexplate, Steel SFI, 1957-1985 SB For Chevrolet, 1965-up 396-427 BB For Chevrolet and 1978-2014 GM 90 degree V6 with 2-pc Rear Main Seal, 168-Too (BM20230)SB BB CHEV 350 396 454 168T Suit SB& BB Chev 168 Tooth, Internally Balanced Part Number: BM20230 '55 '85 Chevrolet SB V8 & 90 deg. V6 with 168 tooth ring gear & 10 3 4" or 11 1 2" bolt circle except 400, '90 & earlier Chevrolet BB V8 with 168 tooth ring gear & 10 3 4" or 11 1 2" bolt circle except 454 Chevrolet flexplates have dual bolt patterns to accommodate Powerglide, TH 350, 400 & 700 R4. SFI 29. 1 approved, NHRA IHRA legal for all classes. SFI