[KiwiStarChief]

I purchased off ebay a NOS fuel sender which the seller listed as for a 1957 Pontiac Star Chief, pictured here with a 5/16" outlet pipe and a brass float:-



Today I pulled the fuel tank to replace the sender, but the one that came out of it was the same as this one (which is also listed on ebay for a '57 Pontiac) with a 3/8" outlet pipe with a oblong plastic float.:-



The outlet pipes are also at different angles (and different diameters as above) which makes them not easily interchangeable. As I can't be sure that the one I pulled out is original, can anybody with '57 Pontiac knowledge tell me which one is the correct sender unit please. If the ebay one is not in fact for a '57 Pontiac, then I will try and return it.

Any help would be much appreciated.