Lots of Mopar parts are like that.The casting/stamping/engineering number on the part is one digit off from the actual in print part number.When it comes to zinc/potmetal parts the numbers can be very different.For example, the 66 Dodge Polara/Monaco right front fender moulding has a casting number of 2579716 and its part number is 2807050.Usually Mopar part numbers are even for right side pieces and odd number for left but they don't stick 100% to that rule.Lots of mid 60's tail light lense part numbers are flipped so you have to be careful when identifying parts.