The Wema is a good unit. It may or may not be the same that you currently have. In order to get the correct model, you have to measure the depth of your tank at the sender flange and then subtract one inch.
If your existing sender is a rod type and not an arm type, and it worked OK, you can just measure the old sender.
You need a new gasket of course and don't over tighten the screws when installing the new unit.
I purchased both replacement senders from them and they came with gaskets. Be sure to check the screws -- the ones that came with mine were meteric, NOT SAE as are in the original sender. Be SURE to align the gasket perfectly to the holes as the holes are not concentric or evenly spaced.