I proceeded to shift the automatic transmission into reverse to back into a parking spot. I then had to pull forward, meanwhile the engine was still revving. Both times, I shifted the transmission made a load clunking sound. The next day I had the alternator replaced, but now upon shifting into reverse, every time, I hear a clunk and feel a jerk and a kind of a growling sound. I presume whatever is broken is internal to the transmission.
Forward works fine.
Your help would be greatly appreciated. From what you describe, you probably did do damage to the transmission. Have a transmission repair center inspect it as soon as possible. Without inspecting your transmission, it is hard to estimate the cost. However, be prepared, it could be an expensive repair.