The 70 swinger 340 i picked up from Louis does not have the partial vin on the core support or the trunk rail. I would agree that it may be under a fender where they cover the core suppor,but the fenders have not been removed. I did remove the trunk weatherstrip and have not found it there, but it could be coverd with glue but im doubting it, ive looked pretty close. My 69 swinger only has it on the core support and not the trunk rail, My 69 1/2 6BBL has it both on the core support and the trunk rail.