help in identifying this part

[<ptegler@cablespeed.com>]

Hello people....
   I KNOW what car this pic is from ( a kit car). but I do NOT know WHERE
this tank came from.   http://www.toad.net/~wizardz/mysterytank1.jpg

Can anyone identify  what car this tank would have come stock on?
...or where a tank like this could be purchased?   ummm...no ...it's not a 
MG Midget radiator overflow tank as the cap neck  position is not right.

thanks

Paul Tegler
ptegler@cablespeed.com
www.teglerizer.com