NO! They're Not All The Same!!
Very important to make sure that you see 2 markings on ANY Mk4/Mark4 drive you look at:
1) The White DVD Emblem (If it's not there, the seller is selling a Mk3 or below! I've seen a couple units advertised on Ebay as Mk4, but when questioned, they admit it's not!)
2) The Disk Eject Button must be on the Left-hand side, looking at the front of the unit. If it's on the Right, it WON'T work! (For the recent 7-series I believe- And that unit is "boxier"/ more square. Avoid that model).

Hope this helps. There are pix of the different units in the NAV Articles section.
Tek It Easy,
Mindfull