There isn't much left of it.
It seems Ford stamped the VIN AFTER the frame had been undercoated and painted. After 37 years of wear there isn't much left of the paint, so not much left of the VIN.
Definetly NOT one of Ford's beter ideas!
![Mad :x](./images/smilies/icon_mad.gif)
Sorry for the poor picture quality. It's a LITTLE easier to see in person.