They came with regular green inorganic inhibitor coolant. You have to be careful these days, since that formula is actually getting hard to find. A lot of "house brand" coolants (Pep Boys, O'Reilly, etc.) are still IAT made by Old World Industries, which also makes Peak. BUT! Many are now "DexClone" allegedly universal formulas like Prestone "All Makes / All Models," which I certainly would not use because of the 2EHA content.
What I did with both my XJs was a thorough drain and flush, then converted to G-05 plus distilled water. I used Zerex G-05, but Mopar and Motorcraft Gold are the same thing. Zero problems in 4 years on the '99 which I did first. It had over 120,000 miles at the time I switched.