The gearbox is used in a lot of vehicles the engine and gearbox match are in a lot f Vauxhall vehicles toh Is is because of when Fiat nearly joined the GM franchise.
The box is called a M32 and commonly has bearings go!
A lot of gear box company's will stock these boxes fully reconditioned or contact breakers yards you have to shop around a bit but can find good deals from breakers I managed to find a box for 300 ish including delivery recently so don't pay over the odds !
Hope this helps
Regards
Mac