Building Virtualbox Guest Additions on RHEL6 fails

We have some test systems where we have Virtual Box v4.3.28 and have a few RHEL v6 test VMs living in it.

I feel that to get this installed is a type of hodge-podge of directions. I've installed an rpm from Fedora website called epel-release along with adding the following: KERN_DIR=/usr/src/kernels/

uname -r

During the install, it outputs the following:

Building the main Guest Additions Module [FAILED]
(Look at /var/log/vboxadd-install.log to find out what went wrong)

I look at vbox.add-install.log and there is too much to freeform here, however it is pointing back to KERN_DIR= and run Make again.