Then there is the B4, B14, B16 that have one series of flywheels, B18 and B20 through
1973 that have the 6-bolt flywheels and the 74-75 B20 whose 8-bolt flywheels will
work on SOME B21, 23, etc
Don't forget the B30, whose flywheel is about an inch bigger and changed from 6-bolt
to 8-bolt between 73 and 74. All the B30 flywheels are too big to fit on the
4 cylinder engines but they will bolt to the appropriate 4-cylinder crank.

ALL of the above are red block (and head) engines.
--
George Downs, Bartlesville, Heart of the USA!