I have a 68 Coronet RT and looking to find some info on it. The Vin is WS23L8C253952. What has me concerned are the last 6 digits for the sequence number. I understand there is 10512 RT made. I read the sequence number started at 100001. From the vin number above, this would be 253952-100001 = 153951. Should I be concerned that this number is way over 10512? Are there any other ways to determine if it is an original RT?