I would suggest rebuilding the original.
I have a 2002 Dodge 5.9 Cummins with 170,000 miles and it still turns me on every time I get in it, I just changed the water pump, belt and idler pulley just for preventive maintenance. I was thinking about the starter rebuild next. I am not having any issues but I guess I just like to stay ahead of mechanical problems. Should I do anything with my starter at this time or just keep on turning the key and cranking on ? How about the alternator, what is life expectancy for that part?
I think my starter is giving up...