Hy Henry G, To start with the newest listing for a 250 inline six in my flywheel interchange is 1979, from 71-79 they only used two flywheels on 250s one with an O.D. of 14.13", and one with an O.D. of 12.85". The flywheel used after 85 on the V8s seem to be different, they are the two different diameters listed above, but are listed as having weights. So as long as you have the right diameter for your starter both the older flywheels appear to have both converter bolt patterns, hope that helps.