People thk all Muncie four-speeds are Rock Crushers, but they’re not. Nowadays there are custom gear ratios and set ups, cludg M21 wide-ratio and M22 wide-ratio units. You can pretty much get what you want. Beefed up boxes for hot rods and Resto-Mods are popular, too. “ When rebuildg a Muncie four-speed you can take a ’65 case and put later year parts.