George,
All of the later cars had both vin numbers on them---the THPN and ZDT 17 digit number which was stamped on the right front inner wheel well in the front trunk area. It was required by some euro countries, not all though. The ZDT number would not work in the US because it requires a check digit to be inserted into the series which tells the registration authorities in each state that the car is a properly homoligated to US specks and is not stolen. You can have any 13 letters or numbers added after the ZDT which would be for Detomaso only except for the check digit making 14 total plus the 3 (ZDT). If it is coming into the US from Italy with all of the epa and dot specks finished, you must have a properly calculated check number in the 17 series, which would have never happened in those days. I believe the check digit should be in the 9th position but all ZDT Italian numbers had a 0 in that position.
It could be possible to have a 0 check digit but that would be a one time fluke.