You've got to pull the rear axle by removing the cover off the rear end. Shop manual will show you the steps to remove the axle shaft spacer, which lets you take the horseshoe retainer loose that holds the problem axle in place. Sounds scary, but it's pretty easy (I've pulled axles on the side of the road before).
Once you get the axle out, you'll see that the seal is probably leaking, it's not an unusual problem. In the 30 years I've owned my '46 I've probably done them 3 times. I use a 3-jaw slide hammer to pull the old seal. Be careful that you put the slide hammer on the SEAL and not the bearing!! The old seal will be trashed in the process. Here's what an old one on a '51 GMC looks like - they're pretty much the same for a long stretch on Chevy/GMCs:
http://s456.photobucket.com/user/bl...ogress/DSC_1244.jpg.html?sort=3&o=10Inspect the bearing and the race on the axle shaft while you've got it apart. Replacement seals can be gotten from NAPA, about $14 last time I did one.
You'll notice that the seal is actually countersunk a bit into the axle housing - important that you get the new one countersunk as well. Put a little gasket sealer around the outside of the new seal before you install it - I rub on a thin coat with my finger. Tap the new seal in place by gently tapping around its perimeter with a small hammer until you get it level with the housing. To get the countersink I use a PVC pipe joint that is just a tad smaller then the OD of the seal. I took the seal to an Ace Hardware and found one for $1.29. You can pound on this pretty well since you're not hitting directly on the seal. Once the seal is in snug, I spread some fresh gear lube on the bearing, the axle race and the rubber ring on the ID of the new seal.
Gently slip the new axle in. Reassemble the horseshoe lock and axle spacer. Refill the rear and you're done. Sounds like a bear, but, like most things, once you've done it once it isn't bad. I can do one start to finish in about an hour.
Good luck,
David
