Classic/Antique Car Repair: 1973 corvette noise, good luck jack, electronic transmissions

Question
I have a 1973 Corvette.  When I have someone sit in the passenger seat and switch gears and put it in Drive i hear a noise under the car something turning.  When I am alone in the car it is fine. Any ideas?  Only when there is weight in the passenger seat.

Answer
That is a tough one.  I don't think your car has seat switches to sense the presence of a passenger, so it is not electrical.  I assume you do not have a load sensor, leveler system.
It could be the weight causing a heat shield to buzz, or the exhaust system to hit something.  I would lay under the car and try to find it.  If you can reproduce it at will, then you should be able to find it.  In later years, the electronic transmissions can make a noise like you describe, but I don't think you have an electronic box in that model.  Get an automotive  stetascope (spelling) and use it to find the problem.  
Good luck
jack


Bob, your floor pan may be oil caning.  Get under the car and have someone kneel on the seat and see if the whole floor pan goes down.  That may be to source of the problem.
jack