Here's a beautiful example of the vintage Sheaffer Valiant, a vacuum filler, with the famous Triumph nib. This is a rather large pen, considering the Sheaffer Valiant lineup, it feels great in the hand, can be used posted or unposted, and is a fantastic writer. Head on to the store to see if it's still available.
What I love about these pens the most is the amazing striated celluloid. The Golden Brown is my personal favorite. It's gleaming, deep, and vibrant. It's a material that finds its way to modern fountain pens very rarely due to its cost and an intricate manufacturing process.
Also, the Triumph nib truly is a triumph of fountain pen engineering. It's smooth, but firm. It's forgiving of angle and rotation, and it's excellent at regulating ink flow. It was designed with these particular characteristics in mind, and it remains a fantastic writing instrument today.