I was trolling the net for a sending unit and the prices range from 45-110.00 What are thie differences? Who makes them all?Some sellers say original tooling, most say stainless steel, what works the best? I bought 2 repops about 6 years ago that were around 65.00 and they both read 1/4 low. I put my stock original back in and it was 1/8 off. I was thinking it might be the gauge. I got a new tank and was thinking maybe they have improved since then.