A lone Koala on Mount Gravatt

Well, we are getting quite proud of our Koala spotting abilities, we have a 100% record for Koala spotting on Mt Gravatt since we first spotted the Koala family back in January! We went a little walk below the Federation lookout again where we have spotted them before, and came across this lone Koala in a tall tree near a bridge, pictured below.

The Koala was very high up in the large tree pictured above next to the path, so it was hard to get a clear picture.  I don't know which member of the Koala family it was, I'm pretty sure not the mother (as her ears were not very furry and she was more brown in colour, as well as her head seemed smaller - an indiation that this Koala is a male) so maybe it was the Dad, or it could be the Joey all grown up?! Anyhow, he looked very healthy and well fed.
When I tell people I've spotted a Koala they always ask 'what tree was it in'.  Unfortunately, 'Eucalyptus' is not a satisfactory answer - Koalas are rather fussy! Well, I have to confess, I've not been in Australia long enough yet to really appreciate the differences between Eucalypts, however I thought I'd take a picture of the tree trunk and some leaves (behind the Koala) below to make some attempt to identify the tree.  Any suggestions?!

With some internet research added to my limited knowledge, I've come up with:
- some kind of Stringybark Eucalyptus
- I looked at this very handy guide to the ID of Eucalypts in the Brisbane region (I will have to print it) and narrowed it down to being most likely one of the first three in the list as they are known to be Koala food:  Swamp Mahogany Eucalyptus robusta, Red mahogany/stringybark Eucalyptus resinifera or Tallowwood Eucalyptus microcorys.  
I'm pretty sure this is a different species to the Eucalypts we have seen the Koalas on previously as the tree bark was distinctly different.  I came across more detail on local Koala food trees on the DERM website.
In my internet search I was also interested to read on the Griffith University website (whose campus is on part of the mountain) that the Mt Gravatt reserve has some rather rare Eucalypt species: Eucalyptus Baileyana and Eucalyptus Planchoniana - now there is a challenge to try and find and identify one!  They are also Stringybark, so would look quite similar to this one.