My car is a 73 stingray. The problem is when i press brakes all the marker lights come on.I have no turn signals at all.I changed the flashers on it but that didnt help.Ive heard people say its a ground but where would it be.

The brake light are feeding backwards through the tail lights, and back into the marker light looking for a ground. Find the black wire from the tail light sockets and follow it. You will find a bad connection. The fact that the markers are grounded means it is likely a bad connection in the harness. It could be a chassis ground. Look for broken or corroded connections. Often the ground problem was the sockets themselves.

I had the same problem with mine. What I found was a bunch of wires in the dash harness melted together on their way to the headligth switch. If I turned on any light, they all came on.

The ground wire for the tail lights bolts to the frame very close to the antenna.