It has always been my theory that Hemi cars were built in groupings. They would build a few dozen one day and then wait for a few weeks before making a run of some more. I think if you had all the VINS of the 10k hemi cars built you'd start to see clusters of them. Why I can only speculate... special drivetrain with a lot of special parts?? All the other powertrain cars were commonly built everyday. Kind of gets back to the known fact of how they cast hemi blocks in batches. Maybe they had to wait for a truckload of completed Hemi motors to come in from Marysville.