To add to what Ed has posted, if the hinges have worn out the hinge pin, and the hinge pin hole has become elongated, then it needs to be bored out, and bronze bushings installed, along with a new pin. Not all hinges have the bronze busings in them from the original manufacturer.
Now, there is one more issue that comes up, and that is if the hinge is broken, and you have to find a replacement. The hinge might not necessarily be a Cadillac part, however, in all likelihood it is a GM part. The difficult thing is to determine what the hinge was originally used on (i.e. Buick, Olds, Chevy, Pontiac, GMC), and what year car was the hinge originally sourced from. I have seen some body builder parts books that give this information along with the part number, and other times, it only has the body builder part number, which is of no use today. In one parts book, the upper hinge was one brand of car, and the lower was another brand of car, but both were GM.
If you have to have one hinge repaired, you might as well do all the rest, because the rest are not far behind in failing in the future.
As to the striker, if the door has been sagging, then it will wear out the striker. If it is possible, take a picture of the striker, and give the measurements of height, width, and depth, and possible we can figure out what you need for a replacement. Sometimes, you might even find a casting number or part number on the part, that will help in the identification. If you latch is worn, then you have even more problems trying to figure out what the correct replacement part is going to be, but once again, it can be done with pictures.