I have installed xcode 4.3.1 on my machine running Lion.
I can\'t find the Network Link Conditioner tool anywhere.
I have checked the utilities folder, also
It's in an additional download. Use this menu item:
Xcode > Open Developer Tool > More Developer Tools...
and get "Hardware IO Tools for Xcode".
For Xcode 8+, get "Additional Tools for Xcode [version]".
Double-click on a .prefPane file to install. If you already have an older .prefPane installed, you'll need to remove it from /Library/PreferencePanes.