Hotchkis 80002 TVS System, Sport, 64-66, GM A-Body, Small Block - Manual (Page 8)

Press the metal can in until it reaches the crease.
Important Note: On 12-bolt differentials, you cannot use the homemade press method. This is because
the thrust bushing (see step 13) needs to be installed onto the can just before the can is fully pressed in.
The thrust washer also needs to be shaved down in order to clear the differential housing. In this instance,
use a dead blow hammer to smack the can into the mount hole.