Will this fit my 2015 Grand Cherokee 3.6L?

Yes, it is listed for 2011-2018 Grand Cherokee with the 3.6L or 5.7L engine. Confirm your engine and existing alternator part number before ordering.

It matches the stock output for these applications, so it is fine for normal driving. If you run a winch, big audio or extra lights, a higher-amp unit is safer.

What does it cross-reference to?

The listing gives TN421000-7031 and 11576R as cross-reference numbers, and 11576 as the ECCPP part number.

Is it new or remanufactured?

It is sold as a new aftermarket alternator, not a factory Mopar unit. Expect aftermarket rather than OEM internals.

How does it compare with an OEM Mopar alternator?

It matches the stock 80-amp rating and fits the same applications, but it is an aftermarket unit rather than a factory part. OEM internals have a longer track record; this one trades that for lower cost.