Your truck should have a knock sensor...it is NOT working for some reason and
should have set a code(s)
Bumping up the octane is only a poor band aid for something that *WILL* destroy
your engine
*IF* that is an ignition knock...it could be something else altogether
I've had folks tell me it is ignition knock that turned out to be a rod going bad
Have it checked out ASAP and get the code....again, in today's ICE's...they
have knock sensors to either retard or go into limp mode.
Knock sensors are cheap and hope that is all it is
DO NOT DRIVE IT FAR while it is this way