Without pulling them out?

I've been hearing a tick while driving for the past month or so, after looking everything over I'm pretty sure its not the headers, an exhuast leak, injectors or even the AIR check valves.
Was wondering if there was a spot you could listen to on the engine with the screwdriver trick of engine stethescope to verify a lifter (or something else) as the culprit. So if you've had some handy tricks passed down by an old school mentor, or if you're a venerable old school guy please feel free to chip in!
Thanks

 

Put one end of a pipe to one ear, and the other end on the valve cover.

 

If you take the oil fill cap off while the car is running and the ticking gets louder, it is a lifter. If it doesn't and it is the same loudness it is most likely an exhaust leak.