Question about muffler hangers
 

(edited for clarity)

Hi all. I was wondering if anyone knew if the left and right side hangers for the muffler (part 20742 and 20741 from this diagram) were:

370Zexhaust_zpsxcrr2gsv.jpg Photo by 20012001 | Photobucket

1) Mirror copies of each other same length etc.
2) Why the part # changed in 2011 and what the differences were. 2011 and prior were "A" designated parts 20741JL00A - 2012 and later were "B"

Thanks!