6bbl and ly rods almost always broke mid beam. Back in the 70s and 80s a compression check is how we saved motors, if the compression goes up 5lbs the rods are stretching and need changed. They are kind of like the sprag in the trans, any driveline failure you had better check the compresion, any increase change the rods. The crazy thing is the ly rods would last 50-100 passes after the compression increase, but eventually boom. On the 6bbl/ heavy duty rockers, at least the ones I have the metal is visibly thicker than standard ones.