I bought a 1968 440 this past weekend.I opened the valley pan and found a bent push rod.The rod seemed to bend a little more as we tryed to turn the pulley by hand.All the other rods looked fine and only the one rod that was bent slightly though I would not reuse it.The rods have a cup at the end.I was told that the engine was rebuilt and was ran for about a 100 miles and all the pressure was taken off the springs and the engine has sat for 4 years.It was rebuilt with new bearings,lightly honed the block,originally had only 52,000 miles on it.What would cause one rod to bend? And should I replace all the rods or just the one, and which ones and where to buy them from? The engine has 906 heads with Isky roller lifters #E6263H and DC purple cam 509/ 292.Thanks Chris