I have nevr heard the term "pinion tanks" before. The Lockheed Jet Star had "slipper" tanks and there was an after market slipper tank made for the Viscount. I don't think the Viscount mod was designed for airline use, but rather a corporate mod (STC), to increase range. The singer Ray Charles had them on his Viscount.
Not a great picture but you can see them protruding from the wing on these photos. These may have also been called Tenneco tanks as I believe they once owned this arcraft at paid for the design?
https://www.google.com/search?q=ray+...lovQ0UM:&vet=1
http://www.vickersviscount.net/Index...53History.aspx