Returning them and plating or powder coating his, may not be the answer. First, I believe the temperature sender should be in the block - not the water pipes for best protection of the engine. Second, The pipe that you mentioned w/ the thermostat housing on my car had been modified by a previous owner to have that area welded over and the support bracket was cut off. I had the car 15 years w/ no failure due to that support bracket being missing. Third, when I did replace my complete pipe set with polished stainless the old ones were so corroded on the inside that I expect there would have been imminent failure, had I not done so. With stainless I will never have to be concerned about the pipes again. Plus, they look cool on the car which has a lot of polished stainless accessories if you are into that sort of thing.
You might want to search this site again. I believe Jack has addressed the issue of temp. sensor placement several times.
Good luck with the project.
Gary
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