Just for everyone's information, a fine example of radiator core support rot in a 2001 F150 V6 I spotted at a local junkyard. Other scavengers have removed the grillwork, plastic valances and shrouds that normally conceal the typical rust pattern. I have checked out about 8 2001 F150's on this same lot over the last 3 years - each one has had this degree of rot - or worse.

 

MAN! They must use a lot of salt out in Ohio!

 

Our salt must have a secret ingredient. The last two winters have had such prolonged cold that it was hard to even get a vehicle washed off for weeks at a time.
I didn't learn of my radiator core support rot until the radiator fell out of its bracket & started making noise. The damage is rather hard to see (unless shrouds & plastic is removed) from many common viewing angles.

 

Actually, you can see the rust without removing anything if you look in the right place which I did accidentally. I bought my 2002 F-150 recently and I had been under, around and through the truck and body many times without finding ANY rust at all. The dealer I bought it from is very reputable. The truck looked like it had been garage kept and the engine showed excellent maintenance. Once I got the truck home, I started changing all the fluids, filters, plugs, etc. and when I was ready to replace the coolant, I had to lie on my back and look straight up at the bottom of the radiator to locate the drain. Guess what I saw which was only inches from my face, on both sides of the radiator? There was severe rust on both sides of the core support that had already traveled to the bushings. The rust had already started flaking off but there was no structural damage yet.
When I took it back to the dealer, he was extremely shocked and embarrassed. This is a small town and his business has been here for generations. To make things right, he found a replacement part (not cheap - he showed me his price) and replaced the parts including bushings plus a rustproof treatment similar to a spray-on bed liner, charging me for parts only. His business includes a collision repair body shop along with a towing service. In the end, I'm happy.