Before replacing, you should go ahead and try to remove it. PB Blaster, a little heat (not too much) sometimes it will come right out, other times TNT won't get it but it pays to try first.
LOL! I would love to watch you work on the underside of a 90s car in my area. You don't unscrew parts, you cut them and if you plan to replace one part you will have to replace all the parts attached to them.