My Mom's low mileage 2012 Xterra has an annoying rattle in the rear liftgate. It sounds like some metal linkage for the locks or handle are just bouncing around in there. Is there a common problem with these that I should look for? I see some mention of adjusting the latch, but everything seems tight as far as the liftgate being closed properly.

So I tried a trick mentioned other places and it worked! I added some rubber "feet" - where the four rubber bumpers on the liftgate make contact with the frame. Sweet, sweet, silence! I don't know if the bumpers were just barely long enough and shrunk? Maybe I'll buy some in my next part order, but if these feet will stay stuck on I will probably leave well enough alone.

Nice!

I'm not sure about the R51/N50, but most of Nissan's rubber bumpers on hatches (engine hoods too) are spiral-slitted and you can adjust the pressure on the hatch by screwing them in and out. You might want to take a look at your bumpers and see if they're adjustable.