Give us some more info about when its overheating. You say it was close to the orange while driving at 50mph. Does it over heat at idle more? Less? More at hw speeds?
Usually if it over heats all the time or more at hw speeds/under load it could be the tstat, water pump, or (most likely) the radiator.
If it over heats at idle only then its most likely a bad cooling fan clutch.
If she overheated so much that it shut off, thats not good at all.
1994 ZJ-I6 w/213,000 mi
1998 ZJ 5.9 w/64,800 mi Slate Black
2004 KJ w/89,000 mi