If you're doing new bearings, I'd say definitely it's worth getting a new crush sleeve and doing it right. However, I must add that if you're just doing the seal on an old rear end, it should be possible to do without that if you're careful. Since the crush sleeve sets the bearing preload, you can assume that after long mileage that preload has relaxed a little. This means that when you reinstall the nut, it will crush down a little further when you set the preload a second time.
When I did my 87 a few years ago, I got a very big pipe wrench and an extension, and put it on the yoke, braced against the ground. It was then very easy to get the nut off with another big wrench without impact. After replacing the seal, I simply reversed the process and set the preload by feel. It worked fine. For all I know it continues to work fine. That D35 was certainly always quieter than my current Chrysler axle.