2005 ford f150 5.4l, replaced timing chain, replaced valve cover gaskets, etc. Noticed now the transmission is leaking. Car has sat for 4-6 months prior to replacing it. Any ideas ?

 

Check your fluid to make sure you're not low from the leak. It's easy to bump the transmission dipstick around while working on the motor. Check transmission dipstick tube, make sure it's seated and aligned properly, should also be bolted down.
After that it's likely the pan, rear seal, front seal, or cooler lines. Clean it up and see where it gets wet first.