I just wrapped up a tank search for a '76 (found one here in Tampa). I paid $160 for the tank and $140 to have it cleaned and re-sealed.
Here's some possible leads for you that I didn't need:
#1 -------------------------------
Neil Freman's Auto
138 Kountz Road
Whitehall, MT. 59759
Ph: 1-406-287-5436
Fax: 1-406-287-9103
fremansauto@bigplanet.com
www.fremansauto.com
Date: January 26, 2010
re: 1976 Datsun 280Z
We have the following:
The gas tank has some dents in it but it still holds gas and the sending unit is in it.
Good used gas tank – AS IS $ 75.00
Plus: Packing/Shipping/Insurance $ 45.00
#2 ----------------------------------------------------------
www.zbarn.com
Roger @ ZBarn has several solid tanks for a 75-76, but each will need to be "re-furbished". I think he quoted me $150 plus shipping. He also has sending units for $30.