Kevin,
Where was you Monte built? My 70 was built in Baltimore, the seat had been recovered when purchased it. I looked in most of the places for my build sheet, no luck! when I started my restoration I gutted the interior, everything! The carpet was shot, almost 30 years old, still no build sheet. I decided to replace the sound deadner under the carpet, guess what I found, my biuld sheet! It was under the sound deadner on the passenger side front floor board. When I found it, it was very hard to read, 30 years of tar & heat from the exhaust. I soaked it in kerosene and today it is very readable. just another place you might want to check.