VDO Sending units
I think the problem exists because the tank is cut to fit a larger 6 screw sending unit that was supplied by RF. The VDO unit is the american 5 hole style. When I ran into this problem I ordered a Tank Adapter Plate, Part number SN41 from Classic Instruments, Inc. The price of the part was 23.00 plus 5.00 for the gasket.
I don't have the webb address at hand but you can find them on the web.
Hope this helps, Peter