The big thing on top is called a side car and not all XDXs have one.I'm pretty sure that is not a dev kit.
A dev kit has a large hdd looking thing on top where the hdd usually goes like this
The big thing on top is called a side car and not all XDXs have one.
The only real way to tell if it is a XDX is if there are wires coming out of the top of the console or on the warranty sticker on the back it might say Xbox Development Kit where it normally says xbox 360.
I noticed it doesn't have a DVD drive. Is this standard for a dev kit?It doesn't HAVE to have those wires coming from the top. Anyways, both dev and demo kits have ports for those wires coming out of the top, so you can't really tell the difference just from those wires. If I recall correctly, demo kits only have ports for the two wires coming from the top, where as all dev and some test kits have other ports such as the sidecar power port.
I'll get you some pictures of what a dev kit motherboard looks like if I can get my laptop to boot.
It looks like a real XDK. There's really no way of actually knowing unless you pop it open. And most people (modders/non-licensed developers) that own an XDK don't have a sidecar on them.