Any reasoning for this? Are you missing any functionality in the current version of gnuradio ?

Just to complete the thread, below is a link with the ChangeLog.
Still, a good load of Bugs have been corrected:

http://gnuradio.org/redmine/projects/gnuradio/wiki/ChangeLogV3_7_2_1

The problem with upgrading gnuradio to the 3.7.x version is that the API has changed significantly, meaning that most of the apps and add-ons for gnuradio will not work with 3.7.
Until the majority of tools have been altered to work with 3.7, I'm not inclined to upgrade gnuradio at this time.

Thanks for your response, I appreciate it.
I know that the API has changed significantly, but I would ask is there possibility to have the both versions 3.6.x and 3.7.x in the same time?

The reason I'm asking for this is OpenLTE which requires minimum version of GNU radio 3.7.0. I could not compile it with the older version 3.6.x on Kali.

http://sourceforge.net/p/openlte/home/Home/

No, we wont hold both versions of GNU radio in Kali at the same time. Sounds like a packaging nightmare.