Denis I have one here in terrace I can throw on the bus for you if you want to pay the shipping.
Wow. That would be awesome. How do you want me to get you the money? Can you ship COD? What further contact information do you need?
I tried the yellow YZ80 tank tonight (pictures in Complete Rebuilds). It does not fit perfectly which is interesting because it fit perfectly on my 1981 XS650 frame. My flattracker is based on a 1972 S2 which is quite a bit different, but I just assumed the mounting bits were the same. It turns out they're a bit wider, but nothing an angle grinder and MIG can't adjust.
I will still probably have a look and Honest Roy's Bikes In Fields to see what he has stashed away. My surf through Ebay makes me think I should get a couple of these in my collection for future projects.
Peace & Grease, Dennis