Without knowing the make or year, it's hard to identify where the original tie down points were located. First place to look would be for a filled hole just under the edge of the sides of the camper. The previous owner may have filled it will silicon, putty, or maybe even a bolt of the correct size.
If it's a real old camper like in the seventies, the tie down point for the front could be directly above the truck frame rails on the bottom of the cab-over. Our old Franklin was set up this way where the chains ran down between the cab and the bed, attaching directly to the frame.