Now your going to start a **** storm on weather or not you can replace a pinion seal on a 489 without replacing the crush sleeve. At 59 years of age, I've done it many many times without an issue. Do a search and you'll see this is a highly debated issue. Here is one of them.
http://www.forabodiesonly.com/mopar/showthread.php?t=20075&highlight=489+pinion+seal
