Nissan Repair: automatic transmission, nissan 4wd, 4wd pickup

Question
I own a 95 nissan 4wd pickup.  3.0 v6 with a RE401a transmission.  Vehicle will not move in reverse. Shifts normal in all other gears. I can hear the transmission engage in reverse but does not give that thud like it does in drive.  Fluid smells clean and is full.  Vehicle has 136k on it.  Is there any known problems with these transmissions.  

Answer
Chad,

I think there is a band that applies when you put it in reverse and it is probably snapped.  You can check with your local Cottman Transmission store or the one you like and see if there is an in vehicle repair.  I know on Ford cars you can get to the band without taking the transmission out and slip a new one in with just taking the pan off and the valve body.  If not, you will need to have the transmission removed to repair.  And, if that is the case renew all clutches and bands.