Installed new head units in 2003 XE and SE
I have a 2003 Nissan Xterra XE and a 2003 Xterra SE and have installed aftermarket head units and backup camera in both.
In the XE I installed the Pioneer AVH-200BT radio using the Metra 7550 harness to connect to the XE wiring and it worked perfect. Very pleased with the setup.
In the SE I installed a Planet Audio PNV 9674RC using the Metra 7551 harness. I had to use ground loop isolators due to pop when changing modes or shutting down. I installed the GPS antenna on top of the dash and also used the ASWC-1 steering wheel audio control adapter to retain steering wheel controls. See this link for more info.
pleased with this setup also.