My 2001 Chevy Silverado 2500 recently quit. It was making a ticking noise and we thought it was a loose manifold. We drove it and it quit but before it quit the oil pressure gage get going up and down, we thought it was the starter since the starter seemed smashed until Further inspection showed that there was a price of metal torn out from the inside out . The hole seemed to be before the bell housing and seems to be before the oil pan under the engine block. Any suggestions before I replace the engine???

 

That sounds bad, start checking the o-ring. Some noticed the pressure relief valve on the oil pump causing oil pressure issues.