Help please - Need to source seat belts for 64 Valiant

OK just maybe there was a option to order seat belts in a 64. I forget what year D.O.T. required belts in everything. 66 maybe ? I've been wrong before and my memory sux too.
I do know that seat belts were brought to auto from airplanes. In some cases the auto makers outsources the belts and buckles from the same mafgrs who made the airplane belts.
That part of the reason we find huge metal buckles that get extremely hot in autos. Wasn't so much sunlight in a plane.