The Nissan Path

Changed out, for the second time, my serpentine belt on my 06 PF / 142k miles / V6.

I spun the pulleys around on the belt tensioner and idler pulley and they both seemed like they had a little play and looseness. Gonna replace next week, but was wondering could they cause the sound that I am thinking are the timing chains?

The belt noise is usually a "squeak." The timing chain noise is more of a "whine," like a bad P/S pump type noise. A bad pulley bearing could also make a similar "whine" or "growl" type noise. You can remove the serpentine belt to see if the noise goes away. If it doesn't, then it eliminates the possibility of a belt or drive pulley bearing noise and would make the timing chain the likely culprit.
Nissan had a TSB on the belt squeak noise. They first recommended checking the belt alignment and adjusting the P/S pump, as needed. They also developed a countermeasure belt and tensioner to address the issue. The belt is slightly shorted than the original belt; I'm not sure what they did to improve the tensioner, if anything. The Nissan P/N's:
Tensioner: 11955-EA20A
Drive belt: 11720-EA200

You can view the Nissan TSB (NTB06-072b) here:

http://ww2.justanswer.com/uploads/fixur ... 6-072b.pdf