1965 fastback. Replaced the fuel quantity sender with new aftermarket unit. After a year or so, gauge went to empty and I found that there was no more plastic float on the sender. Bought a new sender with brass float and after another year or so, it goes to empty. Haven't checked any further but I'd like to know if the aftermarket senders are known quality problems?

 

The scott drake one seems the highest quality but mine the brass float had a crack in it.
I'd do the scott drake and if the float has a crack i'd silver solder it.