I am very pleased to see these pictures Dave. The reason is that I imported a new sender unit, and to cut a long story short, could not get it to work and ended up fixing the old one as described earlier.
The interesting thing about your photos is:-
a) the wipers on mine were of a brass coloured material and had not worn at all.
b) both my resistance tracks were segmented, the inside one with segments about twice as wide as the outside.
My vehicle is also a 99 build, so this proved that for whatever reason, export vehicles were shipped with different parts to domestic US. I spoke to my dealer (Holden) about recalibration also. They don't have this option through the Holden system, and told me when they fit a new fuel pump/sender they don't do a recalibration. So the spare parts here must also be different to the US.
In a twisted sort of way this makes me feel better about my wasted effort.
Also, your unit shows no sign of varnish so you either dose your fuel regularly, or this is not an issue with fuel in the US.
Andrew.