The frame vin is only a partial of the firewall vin. If I remember right the frame vin give you an idea when the frame was built. The frames can be built years before the chasis. Dan at American Toyota is very knowledgeable about vin info. He goes by Toyota dan on the forum. I hope this is helpful. I've have been arguing with Toyota of America that there is only partial vin numbers on frame but they really don't know much about the older cruisers. I gave them my vin number on an 83 fj40 and they tried telling me it was a carrola.
Dan = Cruiser Dan or Cdan