I know this is not truck repair but I thought lot people check this. It 95 F250 with new 351W 19K miles ago it 5-6 years old. It plow truck for 15 years. We try replaced exhaust y pipe we finally remove but 4 studs stuck inside exhaust manifold. It stick about 1/2" We been soak with kroil and Acetone with ATF nothing work.