I had a lot of trouble installing the kernel-headers for 3.7 in Kali. Turns out that the repositories no longer contain the packages for these headers.
I solved it using the debian archive:
Add this to /etc/apt/sources.list :
deb http://snapshot.debian.org/archive/d...30201T032911Z/ experimental main contrib non-free
Then give this command ( to ignore timestamping in the old archive):
apt-get -o Acquire::Check-Valid-Until=false update
Now you're set to install the headers with this command:
apt-get install build-essential linux-headers-$(uname -r)
When done it's probably wise to remove the extra line from sources.list