Mine is RX51-2101

/home/user # cat /proc/cpuinfo
Processor : ARMv7 Processor rev 3 (v7l)
BogoMIPS : 499.92
Features : swp half fastmult vfp edsp neon vfpv3
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x1
CPU part : 0xc08
CPU revision : 3

Hardware : Nokia RX-51 board
Revision : 2101
Serial : 0000000000000000
/home/user #

I got it from Nokia retail in the uk which part of nokia group, they sell nokias to any network, phone was not locked to network, and now i use the global firmware.

with regards to hardware faults:
-usb connector is lately started to playup in a few ocasions e.g. plug in the power supply but might not charge up
-keyboard is perfect
-slider is fine
-i do have a tiny minute scratch in the touch screen which i cannot see but can feel when using the stylus, i have try to clean it but has not gone way
-also i think the memory card slot may be about to go... had dificulty putting in the card last time
-i also feel the camera is not working anything as closely as my old n95 did(same camera on both phones), someone once reported this was due to the mettalic frame around the camera, as pictures without back cover were better quality