In the axle world, cleanliness isn't anything like Godliness, but it gets you on the list for consideration of sainthood. Here's a cheap parts washer at work ($39 from one of those traveling tool sales), but you could just as easily use brake cleaner and a drain pan. Brake cleaner is a good material for cleaning or finish-cleaning a part because it doesn't leave residue. Clean parts can be inspected better, and when dry they won't attract dirt particles like oily parts. The housing can often be cleaned out only with a can of brake cleaner.