Make sure it's not locked, and find out how many unlocks it has left. I would say if you pick one up that is unlocked for $150, then your ahead of the ball game. But if it's locked and cost $150, expect to send it to SCT to be unlocked for a fee.
The X2 will only hold custom tunes, has less memory for data logging.
The newer X3's only do custom tunes
The older X3's were sold prior to 7/25/08, and are able to hold custom and canned tunes.
If your buying a used X3 and are unsure which model it is, there are two serial # locations. The sticker on the back will have the serial #, or plug in the device and scroll down to device info to retrieve the serial.
The date is in the serial#, after the first 2 didgits is the date.
Example: X3011608XXXXX----------- X3 is device,, 01/16/08 is the date.
On the serial number, the first 2 letters will indicate which model also. If it starts with X3, then it's the original model that can hold custom and canned. If it starts with XP, then it's a newer model. You also need to make sure you load up the correct Firmware, because with the two different models they take different Firmware. You can read that here.
2004 F350 CC DRW King Ranch
X-3 tunes by DJ'S,QT,GH,ID. Gryphon FICM tunes, ARP studs,Stage 1turbo,ATS coolant recirc lines,Swamp's 48v ficm,coolant filter,AD2,Snow Perf stage II,EGR delete,4" turbo back straight pipe,S&Bintake,Quad "A" pillar autometer gauges,Suncoast Tri Disk Conv.,Billet input shaft,Suncoast superduty rebuild kit,Trans-go shift kit,Mag-Hytec trans pan,CFM+ elbow,ccv mod,15K reese 5er,17" LCD TV/DVD,Cobra 29 Nitewatch CB