The sender is just two resistance wires with a float bridging them, shouldn't matter which way current runs through it. OTOH, some must have it correct or alles ist veloren.
Also, the Bavaria sender (I'm told) is not the same as for a coupe; the depth of the tube is different. A 2002 sender would fit took, but again, the lengths are different. I think I have a couple spares, good for nothing now that 2002s are getting scarce and Bavarias even more so.
Hans, Fritz and Gerda could have made this so much easier rather than playing games with us.