To remove the extension/adapter housing, use special tool 8274, a puller that lifts the housing evenly off the main case (Fig17).

Be sure to do this carefully, though, as the reverse idler shaft may bind on the extension/adapter housing. You might need to guide the housing off until it clears the reverse idler shaft.

After removing the extension/adapter housing, remove and label the reverse countershaft shim from between the bearing race and housing. Remember that the cast iron main case is very heavy. To remove it, use an engine hoist or other lifting crane along with special tool 8232 (Fig 18).

This fixture bolts to the main case and provides points of lift for the crane.

Special tool 8232 is also used when removing the geartrain. It bolts to the output shaft and countershaft so they can be removed as an assembly. Use the engine hoist here too. 

You should refer to the service manual for the complete procedure, but there are some things to keep in mind before removing and while disassembling the geartrain. 

You have to use special tool 8242, which is a holding clamp that secures the 5-6 synchronizer assembly while lifting the geartrain (Fig 19). If you fail to use special tool 8242, you will end up trying to retrieve the tiny synchronizer components from inside the clutch housing.

Another item to remember before removing the geartrain is to take note of the positions of the shift gates. Then you can use the engine hoist to carefully lift the geartrain until it clears the clutch housing. After the geartrain is removed, install it in special tool 8246, which is a support stand for disassembling and assembling the output shaft and counterchaft (Fig 20). 

Before disassembling the geartrain, mark the components for proper direction during reassembly. It's also a good idea to stack the geartrain components in the order the were removed to avoid problems when you reassemble them.