Hi Jay, yes we had a fleet of phone company vans that their service tech brought us the engines to machine as they needed to be serviced, and he had the same problem with cracked and broken castings. They typically were cracked in the exhaust seats, but also externally between the head bolt bosses and other high stress areas. They also had to go to the Chevy dealer to get replacement heads because all of the used castings they found were also cracked and unserviceable.
