I have measured the three I have & they are all 2 3/4. one of them I just found in my old parts box, it is the original 1968 383 2bbl auto Dodge Charger, 2 3/4

1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5