Have a leak question...

[slammedcavi]

Hello all, I have a 2004 Yukon Denali. I noticed that I have some fluid on the subframe, and on the passenger side halfshaft. Can anyone explain which seal this is, and if I can change it out myself? If so, I may just change out both sides. I am already going to be doing tie rods, idler and pitman. Thanks in advance.

http://i384.photobucket.com/albums/oo289/slammedcavi/036.jpg

http://i384.photobucket.com/albums/oo289/slammedcavi/037.jpg

http://i384.photobucket.com/albums/oo289/slammedcavi/038.jpg