Nissan Repair: 2002 auto transmission question, shift linkage, auto transmission

Question
My 2002 frontier would not reverse. It only go foward on N,D,1,2 gear. It there any way to fix this without replacing new transmission? Can someone give me the instruction to replace the auto transmission.(planning to purchase a used trans. at the salvage place) Is it that difficult? Please give me more leads....thanks!

Answer
Rick,

Are you saying the shifter will not move into reverse and park?  If this is the case it is probably the shift linkage and not the transmission.  Also, it could be internal on the valvebody if the shift solenoid or quadrant is stuck or bent.  I would get the vehicle on a lift first and have someone shift it through the range while you are looking at what the shifter is doing.  I have seen damaged units where the solenoid and or quadrant had to be replaced and it was just a matter of pulling the pan and valvebody and replacing what was damaged.  This is important, if the shifter and its interlock is stuck this will keep the transmission from shifting into park or reverse.  Remove the shifter cover and check there too.  You could even had change, like coins, stuck in the shifter.