Originally Posted By: Blkstanger
I'd guess timing chains. Common on the Mustangs. How many miles are on it?
I'd have to hear the noise, the typical "head tick" is valve guide related. But a random tick could be a bad chain guide, primary chain tensioner(s), or a lazy lash adjuster.
If you can hear the tick better from the wheel well than from the engine bay, it's most likely EXH valve guides.