Used wisely heat is your friend. I own a 96 Dodge Ram 1500 4x4. Bought it new in 96. Anyway, all the drive train was original (before this past weekend and week) and I had never (don't ask me why) replaced the oxygen sensors. Just never gave them any thought. Anyway, past weekend and week was spent going over the truck. Any vehicle I own has to be reliable. I had to heat around the bung of both oxygen sensors before they would move. Just used my propane torch. Finally did get them both out and had to clean up the threads in the down stream bung and went ahead and chased the threads upstream too. Both sensors new now, with anti-seize on the threads. As well as new rear wheel bearings, seals, axles, loc-rite in rear, new u-joints, new front upper and lower ball joints. New tie rods. New sway bar bushings and rods. New shocks and steering damper. Just shotgunned the whole drive train. 200K miles and just wanted to freshen everything up. Peace of mind.