2000 Subaru Legacy GT Transmission

I bought a Subaru and on the way home it began to “bang” when I excellerated hard. Such as on a merge lane or passing. A mechanic told me the car had the wrong transmission so I had to buy a new one and have it installed. It works great now. I am concerned about the overall reliability of the car now even though I know that Subaru has an excellent service record and longevity. The great deal I made on the car cost me a great deal of extra cash. Should I keep it and hope nothing else goes or is it a better choice to sell?