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.
2015 Ram 3500 4x4 Crew Cab SRW 6.4 Hemi LB 3.73 (12.4 hand calc avg mpg after 92,000 miles with camper)
2004 Lance 815 (prev: 2004 FW 35'; 1994 TT 30'; Tents)