Yes I agree with you, 41 ohms is wrong. What the autometer tech was saying is that the new repo sending units that you can buy now, most of them are a linear resistance, which figures out to be around 41 ohms at half tank. This is why I believe that some people are having issues with their factory gauges not reading right with these sending units. They were designed as a non linear resistance unit. I think one problem probably is that Ford used the same resistance range, so you probably have a one size fits most phenomenon going on here. Out of curiousity, why can't you tell us what the resistance is at 1/2 tank?
Thanks