shoreline1932

I have developed a sudden noise under my 1984 sub 4 door wagon GL. It started all of a sudden. Wasn't a slow building thing at all. Just that I was driving along and suddenly a noise started and it is irritating (to say the least) I am thinking (a. wheel bearing) (b. Cat converter) ( c . transmission) I just don't know where to start.....HELP PLEASE

Is a leaky transmission fixable or should I have the transmission replaced. I am not a t all mechanically inclined so I don 't know what to do. Any help out there. What is happening is my auto transmission won 't go into 3rd gear...thanks...