Does anyone know if it is a simple "plug-n-play" operation to install a standard 2004 Xterra stereo in a 200O Xterra? Same mounting bolts and wiring harness? Thanks in advance.

I answered my own question I guess, by buying the unit and installing it.. It does fit very nicely. It's a simple plug and play operation for any one interested. Thanks!

Glad it worked out for you. I'm still waiting to hear from the dealer that has my Xterra about seeing if there's a security code for that stereo. I'll let you know when/if I hear back from them.

I don't know if this helps, but for the 05+ models there is no security code.

I did the same mod only more intensive- took a 2003 RF HU and Amp and put it into my 2001 SE.
Did not have a prob with security coding. All my probs were wiring related/ couldnt get the wiring harnesses and had to fab my own using wire diag from emanuals and cds. It was real fun trying to cram that Amp under the dash in the stock location. it finally went in but it was a bish.