My son has bought a few of those senders, seems like everyone sells them but they all come from the same place.
He's bought 2 now for 2 different c body wagons but I lucked out and found him an nos one last year at the CMC sponsored swap last spring and what do you know... It works and works right.
The ones he bought for the wagons as well as the ones in his ramcharger and 80 pickup both read empty when they really have 1/2 tank. JUNK

There used to be a guy in Ohio (John something?) that rebuilt original ones and from what I'd heard every body who had used his services was happy with the results.