scotch
+1y
Depending on the actual mileage on the crankshaft, the original seal may have worn a groove on the crank. If so, then the new seal (both crank and input shaft) may not seal perfectly. So you can install a very thin sleeve over the crank (and input shaft, if necessary). This gives a new "groove-free" surface for new seal to ride on.
If your crank was replaced 50K ago, then you probably won't have an issue. But if it's OEM with 250K, then you might a have a groove. There is no way to tell until you get into it. And the sleeves are not regularly stocked at the chain stores. So that's why I would have them ready to install before starting the job. Also, you'll want to keep an eye out to see if a sleeve has already been installed.
You can google "Crankshaft Repair Sleeve" and you will find plenty of info about them. Just make sure you pick up one for the rear main and not the front. I would go with a name brand seal and sleeve. And yes, I would do that pilot bearing regardless of the condition.
Hopefully it does only have 50K on a good rebuild. But, if that seal is leaking after only 50K, then that might suggest a less that quality rebuild. Or perhaps, somebody just did the head and the bottom was left alone and they called it an overhaul.