Fuel tanks on the Egli-Vincents delivered by Fritz Egli and those of the early machines assembled by Roger Slater in the UK were all made of fiberglass, a material that does not withstand well modern fuels containing alcohol, melting over time the resin… not good!
Aluminum replacements for Eglis are difficult to find and there is not much choice for the shape (unless you make it yourself): it is either the traditional Lyta that was broadly used by Slater on the Shadow 70 or the “Banana” model that Colin Taylor has been providing for several years.
If none of these are not your choice, here is a new alternative that Colin Taylor just introduced and that he calls the “New Zealander”. They are sold for $1,300 in bare metal finish with a Monza filler and can be painted (any color) and with Egli-Vincent decals for $1550, both prices + carriage
For more information and pricing, contact Colin directly at colinegl1taylor@gmail.com
The Egli-Vincent 
Interested in the “New Zealander” fuel tank. Do you have any more info/pics? Approximate lead time? Thanks
Douglas, contact directly Coli Taylor through the email in the post or Messenger https://www.facebook.com/colin.j.taylor.39