1969 Dodge Dart GTS w/383

radiator core support top left side about where the coolant sticker is or normally would be. Better to feel and take scratch imprint from under. also left rear quarter panel along the trunk seal about halfway down do the same as with the first or you'll have to peel the trunk weatherstrip away. normally the paint covers it up from above. Should be able to feel the stamps from under. This is the best I can remember.
Good Luck!

sorry it should read the last 8? of the VIN number in a 69 these numbers should be in agreement with the dash vin as well as the fender tag. there is a possibility of a replacement core support or quarter panel but generally not both so one should confirm. look also for these panel having been replaced, check welds etc.