A dose of nitro in the 91 in the second tank.
And, the piroute I perform when I fuel up is kinda fun… Fill the poerttank and then with nozzle up to avoid drips doa spint to get the nozzle to the out board tank. When that one is up, repeat the spin to get to the pump…
Carl
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I’m not sure the sloshing would have been a problem. When I look at tank manufacturers websites, most all of them have internal baffles to mitigate the sloshing. I’ve tabled this thought of modifying the tanks. I have many other items to attend to, what with my XJ6 not having been started up in 20 years. Interesting note - I found the original window tag in the paperwork showing all the options and original price. I’ll post here separately. Thanks everyone for the great discussion!
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On occasions I could actually put one nozzle from two pumps in each tank, Carl - and lock the handles. Not so much to save time, but to impress the surroundings…
Frank
xj6 85 Sov Europe (UK/NZ)
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BTDT, get some good looks 
worth considering 
:
I have consiered that !! The lane is too wide. And, I guess other folks in line might look askance!!! Or these days, worse !!! Haul out the Glock…
Carl
Somewhere, somebody posted that picture, on here!
I bought 2 spectra tank for my S2 XJ12. It looks like they only supply the S3 configuration with the two ports several inches apart. The tank fit well but for my car I had to adapt all the vent connections IIRC. They usually had the vents but most were of the wrong size for my S2. I think they are all made to fit S3. Don’t expect any sympathy from them if it doesn’t quite match up. I think list was about $750 but it was easy to find a seller at about $300. Don’t even think about using an old tank.
Did that in Austria at a small gas station years ago with my parent’s double six VDP.
They had a small workshop next to the gas station and 3 mechanics and the boss came out to look at the exotic contraption on their gas station… 
When you then walk into the shop and say “Pumps 1 and 3, please”, the look on the cashier’s face is priceless…
On topic:
SNG Barratt’s carry several after market fuel tanks:
https://www.sngbarratt.com/English/#/US/parts/3cc25a7d-becc-4c68-aa0d-927a36ce72cc?fromCategory=FUEL%20SYSTEM(4103)
The US$18,99 part is an adaptor kit, probably to fit to all series models.
This is because they have their small fuel cell inside the roll cage so it’s much, much safer than it looks 
and the saddle tanks are long gone.
Here, when jalopy racing was in full swing, the tank moved inside. In the trunk, “boot”
In the early days of the west, transport was by Wells Fargo. Stage Coach. A leather flap a bin astern, for luggage. Known as the boot… Wells fargo survives to this day, as a bank… And a coach is available for symbolism and special events. four or six horse team… .