I replaced the ones in my 2000 last summer using Viton O rings and no lubricant. They were leaking and I needed to get the heater working for winter. Had a bypass hose in place over the summer. I could not get the original screw out and had to cut a hole in the side of the plastic center consul underneath the side cover in order to drill off head with a 12 inch drill bit. After I got the assembly out I had to put it in my vice and use a Vise Grip to turn out the remainder of the screw as it was so rusted in place. The old O rings were brittle as chalk, probably 18 years old. I used fresh water to test and had a leak. Discovered I had not lined up the pipes correctly before tightening the socket head screw that I used. Realigned so that the pipes went in straight and have not had a leak since then. I have a heater core from a parts car and it seems well made to me so I would not be inclined to replace it offhand as I don't think it is that easy to get out.