Caution! The procedure is the same for the transfer case front shaft seal and the transmission tailstock seal.
1. Raise the vehicle and place it on stands.
2. Remove the driveshaft (front or back).
3. Unscrew the box flange nut, remove the flat washer (see photo).
4. Remove the cardan fork (or flange).
5. On some vehicles, remove the gearbox shield.
6. Pry up and remove the seal.
7. Lubricate the working lip of the new oil seal with ATF or petroleum jelly.
8. Press in the new seal using a mandrel.
9. Then assembly is carried out in reverse order.
[The source of the article is available on the website: «ChevyMan»]