What is this cooler/radiator??

[Joe Collins]

So I took my grille off to plastidip it black. What is the small, vertical, surface rusted to shit core on the drivers side?

I know what the trans cooler and everything else is but I'm not sure of this one. Any ideas? Also, in it's current condition should it be replaced??

 

[Joe Collins]

This was the end result in case anyone is interested

 

[SnowDrifter]

Power steering cooler

 

[915_Tahoe]

i say clean it as much as you can and paint it black