Up for sale is an N42 and E31 rebuilt cylinder heads.The N42 was inspected by Rebello racing who built a stroker short block to match this head. Both cylinder heads were professionally rebuilt with new valves, seals, seats triple angle grind etc. N42=$750, and E31=$675. Not looking for core exchange for the E31 but definitely a good rebuildable core for the N42 in exchange. I have two good used P79 heads that can be bolted right up to a block but probably won't hurt to install new valve seals.$375 each.