1999 Grand Am axle beginning to pop out of transmission

Hello, I have a '99 Grand AM SE 3.4 litre automatic with over 300,000kms on it, and it leaks transmission fluid. When we had a look under the car, the front passenger side axle is popping out of the transmission. (It is still intact but there is about an inch and a half of metal exposed, whereas on the drivers side there is nothing exposed). I actually went to NAPA and purchased a new axle and thought I would just replace the whole axle, but unfortunately, one of the old bolts are seized so I have to take it to a mechanic. I am a 20 year old female (broke)student and I don't want to get ripped off. So I was wondering if there is something that maybe holds the axle in that could be causing this. Maybe I don't have to replace the entire axle? The axle appears ok. Just popping out. I really appreciate your help, thank you!