I just had a new mil. surplus 6.5 engine put in my '93 C2500 Chevy pickup. The people I bought it from always remove the heads from these mil. surplus engines and have them taken to a machine shop to be hot tanked and checked for leaks, valve sealing, etc. Something about the engines being run on a dyno when the mil. takes delivery, and they've had engines that didn't have the cooling system completely purged of air. Hot spots, head cracks. I haven't been able to call the people back to confirm this, (I'm working in Germany for the next month), but I'm afraid they've reused the head bolts. Aren't these torque to yield? The block date indicates the engine was manufactured in 2001. If those head bolts weren't replaced, I'm looking at leaking head gaskets down the road, right? Any input on this issue would be appreciated. I won't be able to get back to the truck until the middle of Dec.