Assuming the 2005 rear suspension is the same as 2000 - 2004 get the SVT rear lower control arm if one is needed. I am not sure if newer non SVT ones have ever been updated but it had extra enforcing in key sections that are known to have stress problems.
Is the mechanic not able to back out the bolt?
2001 ZX3 2.0L Zetec-
Hatch Nation #42
Going through Rebuild See "The TICK Build Thread" for details (http://www.focusfanatics.com/forum/showthread.php?t=289168&referrerid=62897)