Name this part?

[Sunnydaze860]

Can anyone tell me what this part is called? Sorry I'm a noob and just learn as I go. It's the bar that runs behind the rear tires on a 2001 expi Eddie bauer edition.

 

[TobyU]

Can't see much in pic field of view for reference but I think your talking about the lower control arm. They keep ye rear axle from moving front to back and rust out a lot on these.
I got the ones for my 2000 on eBay steel rectangular powder coated much stronger ones for 92.00 for set back in 2012.