I recently bought an 87 300D Turbo, its my first car! I've been going through it replacing filters, running treatment, changed the oil and transmission fluid, and steam cleaned the engine compartment. I have a couple of problems though:

There is a loud whirring noise that can be heard and seems to emanate from the electric fan, and I'm hoping not the radiator. It is fairly loud and can be heard from inside the car with the windows closed. Any ideas as to what this could be or how to fix it? I've driven it without this noise when I purchased it, but now has persisted since a couple of days ago.

Also, the bushings for the rear differential are shot, and I was wondering if there was a way to replace them without dropping the whole rear end.

Any other tips for bringing this beauty back up to speed would be greatly appreciated. So far I love this car and want to treat it with the best it deserves. Thanks for any input.