Idid theRHS head on my 3.9 sems 6 months ago , but didnt do the LHs as all the compressions were in the 150 psi range . But last wekend it was overheating so limped home &took comp readings next day . Sure enough front 2 LHSshowed 0 psi so pulled the head off , a real ***** due to the brake ABS unit & needing tiny hands to get at back manifold bolts & head bolts . Must be first time off as it took a 1.5 m pipe on the long bar to undo & sure enough its blown between front 2 cylinders just like the other side did . My old 96 3.9 disco did the same they seem to have a habit for this at around the 200k km mark , often see them for sale with owners saying "blown head gasket " At least the parts are cheap & plentifull from after market suppliers .