I believe that the Chassis No's and Ash Frame Serial No's run independently, which is why the number stamped under the drivers or passenger seat squab (in my case 0729) is typically different to the number stamped into the Ash frame under the boot liner (which for me is 0795). I am told that this is due to some frames failing QC later in the process (after number stamping) and ending up on the Malvern Link bonfire...