After running low on oil very briefly, my 2001 F-150 has an unusual engine noise.

If you drive at about 65 mph and back off on the throttle, there's a ticking sound that sounds like engine ping.

The strang this is that the sound comes only when backing off on the throttle at about 65.

There's no noise at idle, cold, accelerating etc. Drive over or under the 65 (3,000 rpms) and it's silent.

I'm thinking a lifter, push rod or a rocker got damaged?