The flywheel has a date code cast on it. Letter and numbers. Example B 58 = Feb. 5 , 1948. If the fly wheel has the 6 hole pressure plate then that date code could be Feb.5, 1958. It can be confusing as to the generation '40's,'50's'60's. Early flywheel wheels ( at least thru and including 1948 had 9 bolt pressure plate) for the 10 3/4 " clutch on the 3800 series (1 ton). I bought a new clutch disc from NAPA and had the pressure plate rebuilt at an independent clutch shop.