Mounts are available. Do they look like thses?
https://picasaweb.google.com/118082002072608219229/DetroitDiesel353TSilver#5803305018114615698
There are two different sizes of them, these are the part numbers for the big ones that use a 5/8" bolt. They can be found pretty cheap new on ebay, I got mine form NAPA. https://picasaweb.google.com/118082002072608219229/DetroitDiesel353TSilver#5803305031421815170

If you need the smaller size they can still be had either at the auto parts store or many of the restoration parts suppliers.

The bearing you're asking about is called a carrier bearing, or driveshaft center bearing. Depending on what yours looks like you can get a rebuild kit (possibly only NOS) or you can replace with a new version/style form an auto parts store or driveline shop.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-