Sending unit retaining nut

[milit73]

Where is the best place to get and new retaining nut and gasket. The one I bought from ebay does not even come close to being tight. This is for a 68 superbee with a 383. Does anyone know the size of the sending unit 5/16? Thanks

 

[beezee]

Try Spectra premium.
http://ecat.spectrapremium.com/ProduitsVehicules/vehicule/1081842