Hey guys need help! I'm looking at a 01 lb7. Guy says the water pump was leaking so he had that replaced by a buddy and he had coolant in oil afterwards. Then he replaced the oil pump still nothing. Does this sound right ? I don't wanna get beat. I'm the truck has a built motor built trans with new injectors and head gaskets and studs. He says he thinks his buddy fucked up the seal / o ring and that's what's causing it. Hard fix ? Please let me know. Thanks .