My Glock81 saw back is probably my favorite field knife. I would edc it if it weren't for the knife laws TX. Where I used to live had no restrictions I could and did walk around with everything from a small hunter to a large kukri depending on my plans for the day..So It lives in my trunk with my tools and my kit. Not on me, but close at hand.
They are not full tang but have a separation between the 2nd and 3rd band on the grip to provide for impact and electrical insulation.
I remebered this x-ray photo from a while back. The Glock 78 is no4 counting left to right. You can easily recognize the profile and guard.
You can see the separation and the bayonet socket clearly.
Now don't confuse this feature for a structural weakness the only image I have ever found of the tang coming through was someone who cut away the handle to find out if it was full or not.
If you pry out that cap on the pommel you should find the socket for the Styer AUG Bayonet mount(depending on issuing country and adapter many use US M16style too). I've never had reason pull mine to find out if its there on the civilian retail models since I don't have an AUG, but I don't see why it wouldn't have it.
And while google'n the photos I found another thread over on bladeforums that someone has a bit of history with early compeating models with pics but half the img links are broken still cool though
http://www.bladeforums.com/forums/showthread.php/1104535-Thoughts-on-the-Glock-81-78