I need help figuring out what this third member came out of!

 

Looks like a 4cly 3rd

http://home.4x4wire.com/erik/diffs/3rds.jpg

 

But what about the passenger side only having two ribs and that one area where a bolt or stud is supposed to be?

 

It looks more like the larger pinion (v6) housing, the upper rib for example is prominate over the snout, but it's definitely not any of the three posted.

Send zuk a message and maybe he will chime in, he's almost certainly the most versed on these.

 

I’m sorry I’m kinda new who is zuk?

 

This guy: ZUK

And his website: http://www.gearinstalls.com/