Is it possible to fit a Syncro fueltank into a 2WD Vanagon? The tank might
need notching here & there to clear difflocks etc. Looking into the 2WD
rear wheelwells, there's an awful lot of empty space above the trans where
Bays and Syncros have theirs.

Conversely, would a 2WD tank fit a Syncro if you welded in a longitudinal
driveshaft/shifter tunnel or cut a clearance notch into it?

How about making and fitting flat outrigger tanks to fit between the
chassis rails under the floor, perhaps with pumps to transfer fuel to the
main tank?

Andrew