The noise of a bad pinion bearing is loud. You won't be able to hear anything else in the car.
If you have the pinion bearing issue, it may be difficult to find a good shop where you live. There is one in CA that does, it, requiring taking the transaxle out of the car, strapping it to a pallet and freighting it to CA. The other option I found was a transmission shop in Holly Hill, FL, right next to Daytona. He really impressed me when I talked to him. I took the car up on a trailer, and he drove it for about 30 seconds before he told me it was the pinion bearings. I had given him no prior description other than it made noise.
His shop was nearly as clean as an operating room and he assured me he would keep my car inside. He ordered all the right parts, brought me up to inspect everything before the rebuild and showed me the problem.
He also put a two year warranty on his work and gave a good discount for cash. I think it was "Precision Transmission". He has been in business for years and has done some 35,000 rebuilds I think he said including Ferrari's and other marques.
I went this route as it was 40 minutes from my house and as I said the local Porsche shops, including Brumos, wouldn't do the job and Brumos never bothered calling me back. In addition I still have a numbers matching car, if that means anything on the transaxle. Who knows.
The other route is to put a used one in. Then you still don't know if you have a good one and what warranty if any would you get. If you have to ship it, there is labor in and out, plus the labor on the rebuild. Cost, cost, cost.
If it's old noisy tires, you will know as soon as you put new ones on. Tires time out at about 5 years, so check the date codes. You will most likely have to replace them anyways. Mine are timed out. I put them on in 2013 when I bought the car and they don't have 6K on them yet. I will be looking for new ones.
Good luck, there is lots of info online about pinion bearing failures. Mine if I remember correctly was about $2700.00 or so. I could look it up if needed.