v8 engine clatter

help .bit worried,4.0 v8 starts runs fine no smoke no oil/water problems runs and sounds fine most conditions but if under load up steepish hill with foot down clatter from engine[top endish i think] not much power,what do you think! is it the dreadful lining prob i keep hearing about,yours really worried john

Could be the exhaust-manifold to Y pipe gasket blown if under load it sounds like a machine gun.
Need to hear the sound to give the correct diagnosis

Thanks for that will check ,gives me hope cheers