Bench testing two cheap eBay fuel sending units

I recently took a box of gauges from 50 years of 70 Darts (non-rallye) to a guy that does nothing but restore gauge clusters for antique cars. He showed me how cheaply made the originals were and identified some that were simply dead (both fuel and temp gauges). I decided to buy new fuel and temp gauges that are available from several sources (I got mine from Herbs). I looked at them carefully and they were much different from the originals and much more substantial in terms of the actual mechanism. I'm not to the point where I've put all this to use and it will be a few months, but this might be part of the solution.