Build Date from VIN?

".........can you ascertain the build date from the last 6 numbers of the VIN?......"

I have the same question about my 68 Valiant. I just basically want to see if I can determine if mine was built before or after 1 Jan 68. According to the VIN the car was built at Hamtramck.

When I bought it there was no data plate and the original engine, trans and rear end were long gone. I was wondering if the number on the trunk lip (which is not a partial VIN) might be able to be decoded for an approximate date?

Anyway any help would be appreciated.