'70 Challenger rear end vin stamping?

[Mr70]

I could be wrong as I am not up on Chrylser details,but I think the driver side deck lid drip edge stamping you are referring to is actually the generic bodystyle callout number for the rear 1/4's application..Not a unique CON VIN.(Confidential Vehicle Identification Number which is a derivative of the full VIN as listed on the title.)
GM vehicles did this too,as my Chevelle hardtop has 13637 stamped in bothsides of the rear 1/4 weatherstipping/trunk drip edges,followed by a two character panel production date.