not so accurate guage

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
I think the truth is the reproduction senders are correct. It's the aftermarket gauges that dont match up.
I've serviced a bunch of OEM gauges and atleast half of those owners have repop senders. No problems reported to me.
My own repop sender came from Vans Auto on ebay. It operates same as OEM.