8.Here's a look at the small Jeep 231 factory chain and gears (left) versus the JB Conversions HD chain and gears (right). We've shown the main shafts (stock left, JB Conversions SYE shaft right) in the image as well. Notice the SYE main shaft is a shorter, beefier unit with 18 percent larger spline diameter and a 32-spline output. The JB Conversions wide chain kit comes with a wider drive gear for the main shaft, the big chain, and a new front output gear. Please note that you don't have to use a SYE kit or a new main shaft to use the wide chain kit; the wider drive gear fits either main shaft.