CY & CX 400THM: differences & similarities

[61 vert]

457 date would be around april 3rd which would put it slightly before the April 14th date mentioned as a possible cutoff date.I have a CY dated 478 ,2 weeks after the April 14 date. If we could come up with a bunch of CY and CX dates, a cuttoff could be narrowed in on.As far as comparing the trans cutoff date to when the cars switched, that would be tough.I suppose that they could have been intermingled until the CXs were all gone, or different plants could have run out of CXs at different times.Does this make sense?