70's retracted into the floor under the carpet. 71's had an exposed re-tractor next to the door. It had a plastic/rubber boot that the belt wound into. Not sure about 72-74 though.
As far as hood hinges, I had a horrible time with a hood on a car, Challenger. I put the hinges on, then with help installed the hood. I did everything possible to get it to close at least fairly close. The thing was about 3-6 inches up on each corner. I adjusted until I finally gave up. Upon real close inspection in comparing to my survivor, it was determined the hinges were off a 71-74 B Body. They look so close, but will not work.