Ticking in the cab.. engine noise?

Short story. No ticking sound originally, went to cruise some fire roads. It's a pretty bumpy trail. After getting down the mountain, I notice that under acceleration there is a distinct ticking noise in my cab. It sounds like it's coming from the passenger side but sounds al.ost like from the engine bay.

Under normal driving, it is only when my foot is on the gas. When I lift, it goes away. At a stop, in park, it only happens at low rpm.

Also when I open the hood and rev the engine from under there, the engine sounds normal...

Any thoughts on what it could be?