Gear-driven Jeep T-cases like the Spicer 18, Dana 20, and Dana 300 have an inspection cover at the bottom of the case. If you hear odd noises coming from your T-case, you can often drop the inspection cover or (on a Spicer 18) remove the PTO cover plate to inspect the gears for missing or chipped teeth. As soon as the intermediate shaft or bearings begin to wear, the gears can run cockeyed and chipped or broken teeth are often the result. Again, rebuild components for these T-cases are cheap to buy and relatively easy to install. When properly rebuilt, these iron T-cases are plenty tough for moderate-to-heavy off-road use.