I just bought a 63k mile 2002 in pristine condition from the original owner. For preventative maintenance I decided to go ahead and flush the cooling system and install a new water pump, fan clutch, hoses, belt, etc then convert to ELC. I have done this job once before on a previous 7.3 I owned. Before I started replacing parts I wanted to flush it first, so I flushed it with the Motorcraft VC-1, then several rounds of distilled only. When I removed the water pump, I noticed this orange buildup inside. As far as I know the cooling system has never been touched, given the low mileage. I’m heading to my Ford dealer right now to pick up the VC-9 flush, which is acid based. Should that do the trick here? Is this just a product of the truck sitting for most of its life? You can see in one of the pictures where I scratched it off a little bit, it will come off if you try.