Nissan Repair: 2002 auto transmission question, professional tool, auto transmission

Question
My frontier will not reverse when I shift it to "R" and the "Neutral" gear will go foward. I notice the problem 1 week ago when I try to reverse in my drive way and the engine shut off when I put in reverse. Then I later that day the 1st thur 3rd gear was little stuck. I was planning to buy a used trans. at the salvage place but scare that it might not solve the issue. Can you tell me how to repair this and if I do have to replace the trans., is it that difficult to install one? Please give a lead where I can get the instruction to replace the trans. thanks!

Answer
It is very hard to install transmission. Even if you have a professional tool set and a friend to help and you have worked on a bunch of transmissions before, it would still take a long time.

If you've never done it before I recommend getting a professional tool set (including hoist to lift the engine out) getting a friend to help and recording every step of the process as you go so you can put it back together right.