my boss has 04 harley f-150 4x4 his was on seal i am going to check my vacum on the lines first should be holding 20 lbs the new solenoid i picked up the updated one was 27 dollars cdn a quick test is put it in 4 wheel and if the grinding goes away it means it is either the solinoid or your seals wich are right behind your knuckles the solinoid is on the firewall right behind your battery with the two lines attached