Do I need to drain the cooling system to swap this in?

Depends on the condition of your old tank and how much coolant is in it. If the tank is cracked or leaking, you'll lose coolant during removal anyway. If it's intact, you can remove it without a full system drain, though you might lose some fluid. Refer to your service manual for the exact procedure and coolant capacity.

Will this work with my existing hoses?

Factory connection points are designed to match OEM hose routing and diameter. Check your existing hoses for cracks or brittleness—if they're original to a 1996–2002 4Runner, they've likely seen better days and should be replaced alongside the tank.

Can I paint this before installation?

Yes. The unpainted finish accepts standard automotive primers and paints. Let any primer and paint fully cure before filling with coolant to avoid contamination.