Will this cool my transmission fluid, or just engine coolant?

This radiator handles both. It's engineered with an integrated transmission cooler circuit to manage automatic fluid temps alongside engine coolant. You're getting full thermal management in one unit.

Do I need to flush my cooling system before installing this?

Flushing beforehand is smart practice — it removes sediment and old fluid that can restrict flow in a new core. Use a standard system flush and fill with fresh coolant rated for your SLX.

What mounting hardware do I need?

This assembly includes all factory mounting provisions. Use the original hardware from your removed radiator — bolts, clips, and brackets will transfer over. If any fasteners are damaged, grab replacements from your local supplier.