I did some searches and couldn't find anything, so... There is a cross member or something under the radiator on my truck that is rusted to dust at this point. I is "U" Shaped and looks to be bolted on with 2 bolts each side about halfway up. Is this just a "Bumper" to save the radiator, is it a structural member, or is it part of the radiator core support?

From the pics I could find on the core support, it doesn't look like part of that, but...

 

It provides lower radiator protection. It is not a structural support, nor is it necessary for frame stability at all.

 

Cool. Thanks. Mine is rusted through and the whole bottom tube is gone, so I am just going to pull it off.

 

It may not be needed for frame stability but the lower bumper cover lip screws into it. Mine is also just about rusted through.