You need a second opinion. The bevel gear box needs to have the fluid flushed. There is a procedure to drill out the bottom bolt hole to make a drain in the box, and then it is a simple procedure to flush and fill every 50K miles.
If the bevel gear box is leaking fluid, you might just want to replace the unit with a junkyard one. Usually leaking fluid is a death knoll.

You need a new prop shaft? That doesn't sound reasonable unless you feel a vibration at speed.

Having a minor leak on the side of the rear diff is not bad, so long as it is truly minor.

At 105K, it is time for a timing belt change.

Klaus
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Proud owner of a 220S. If I had more room, I would have more Volvos.