I have never encountered such a dearth of information about an apparently very important piece. The Lt1 has a size specific ball berring driven into the oil passage under the rear main cap on the passanger side of the block. It must be removed for proper cleaning when the engine is rebuilt. Then reinstalled apparently to ensure proper oil pressure and oil routing in the lt1. Of course the machine shop lost the berring and I can not locate one. I have been to the dealer it is not on any of the exploded views an I have been unable to find any other refferences (part number or the actual size) online. The size is also important because it deturmines how deep the ball fits into the funnell shaped hole. I have Mike Mavrigians book where it shows a picture of him removing the ball but to mention of what it is actually called or what size it is it just says make sure you put it back in. I imagine anyone who has built an lt1 must have encountered this problem b4 if anyoine can help I would be gratefull.