New in the box 3908539 power steering reservoir cap. I believe it is correct for 66-68 Beaumont 396 as well as 72 and older 396 or 402 1/2 tons. I am open to correction if I am wrong. All these applications use the remote reservoir for power steering fluid with this unique style cap.
Cheapest thing I could find that had sold on ebay was $25 US for a used one. New ones, $85 US to over $100 US.