Torsion bars come in many different sizes. They will all work as long as they are for an e body. Other body styles use different length bars. The diameter of the bar has the affect of changing spring rate. Larger diameter bar equals a higher spring rate and a stiffer, more predictable ride. These cars were horribly under sprung from the factory. Do some research and you will see most people would recommend a minimum of a 1.06" bars, and some run up to 1.25". Small block? Big Block? Performance handling? Do you want a factory "ride", performance, OEM restoration? Your choice. Many companies offering bars in various sizes...Google is your friend..