Welcome to the forum chookies,
 
New parker/indicator lenses and ute taillight lenses are hard to come by.
They seem to be one of the harder 1000 parts to buy.
Unfortunatley many spares of these end up in peoples private stashes of spares and don't see resale.
If you manage to find a set without cracks just give them a polish.
 
You can "very gently" polish with a soft buffing wheel and fine polish on a bench grinder/polisher, as long as you think about how the wheel spins so you don't spit the lense across the room.
 
Otherwise if you decide to do it by hand, autosol works well to work through scratches.
Then work down to car polish.
 
You will be amazed at how new an old part can look.
 
As far as finding a lense without cracks goes, (other than your wanted to buy ad)
Just keep searching all the usual datsun 1000 parts hot spots like ebay, yahoo, gumtree, about time spares... ect.
 
Unfortunatley you are after a part that takes time to source, so you'll need to check the above sites regularly.

yea lenses seem to be the hardest to come by, wait around long enough you'll get some but be prepared to pay a pretty peny