Need to replace radiator. Should I flush/clean?

[g300d]

I wouldnt chemical flush. I did that on the 4.6 and right as we buttoned everything up, the water pump started leaking.

Not saying all chemical flushes will do that, just sharing a con from experience.

If its always been run with coolant, the system should be clean enough that the drain and fill from replacing the rad should get any crud out.

I second the trans thermostat and trans cooler seals. Have had the thermostat break pulling the expansion tank and had trans cooler seals leak.

"Just because" is often recommended for the cooling systems of these trucks and other BMW's of this era. I experienced why.
I've had hoses leak one after the other and after the first few, did all the remaining hoses in one go.

If you want to do a partial cooling system refresh while you're there, I'd add the 2 auxilliary water pump hoses and the expansion tank (OE only for the tank!).