Which Hemi and how much HP will you be running. This will not hold up to a 426 style Hemi that is supercharged!! If it is a new gen Hemi, it will last!! Geof
The cars weight and traction have a tremendous affect on how much power a rearend can handle. If ya put street radials on it it'll never hook up good enough to break anything but if you run slicks it's kinda on the edge with your power. One of the few drawbacks to a 489 was the crush sleeve they used. If you have it replaced with a solid spacer it'll help it stay together.
If you are running an auto without a trans brake it will also last better. A trans brake or hard launch with a standard plus slicks and its days will be numbered, especially with a tired 40 plus year old factory gearset and sure grip. The crush sleeve - Cas at Dr. Diff.