No. You can pack those. You will need a replacement axle tube seal first though. Most people don't mess with those unless of course axle dope is leaking and/or you have up and down play in the axle. Which of course is a sign end bearings are going bad.
Post in Wanted before you go buy a unit bearing. I know a lot of people that take shit apart have extras sitting around. Its one of the most overlooked items to save off of functional D30's after people upgrade.
If you don't want to mess with used stuff, shop around and find a place that may have a lifetime warranty in place. NAPA currently has an unlimited lifetime warranty on Timken units for Rams, so you may want to check with them. I have at least 4 nib unit bearings + a number of used ones, so I haven't had to shop for one for a Jeep in a while.