I believe I'm hearing our 1988 wagon's rear wheel-bearings making a whirring/droning sound (not high-pitch, more of a low pitch).

What's the proper diagnostics and service? How much should I budget in parts?

Do I just replace the bearings? Do I do both sides? What else should I do (replace, service, inspect) while I have everything apart?

A good mechanic should take how many hours to do the job? Can a DIY do it without a press?

Also, is there an extreme/heavy-duty bearing that can go in it's place (perhaps from 1992 SportLine, 1995 E320 wagon, or 1992 400E/500E)?

Sorry for all the questions, but all my references are in storage while we're remodelling.

Thanks in advance,
:-) neil
1988 360TE AMG
1993 500E