Probably a combination of upper timing cover, vc gasket, head gasket and VG oil seals. VG oil seals can account for quite a bit of oil consumption on that engine with no exhaust smoke or smell. A while ago I was burning/leaking 2 qts. every 1200K miles. After replacing the VG oil seals consumption/leakage is now 1 qt. every 1500K mkiles or so. Engine still leaks from head gasket at the right rear and I have the parts to repair but so far the burnt oil smell from oil leaking onto the hot exhaust mainfold is tolerable. Mark