Is your truck one of the 302s that have the PCV in the rear driver side single runner?
That can cause detonation in the cylinder and it can also blow all the oil through one piston instead of sharing it amongst all eight.....
The mustang guys have a mod, where are the PCV goes to the plenum instead.
If you get too much oil in one piston it will diesel and break out the top ringland or put a hole in that piston!
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.