Any car can have up to five broadcast sheets in it. So, if you have not done so yet, be sure to look inside the front seat backs, in the rear seat back, taped to the back of the glove box liner and under the carpet.
Those are the most common places to find broadcast sheets in a 1970 Hamtramck car.
It is common to find one or two for other cars as well, so if you find any sheets with a VIN that does not match your car please post the numbers.
Best of luck with your search!
Barry