man are you in luck....i got some pics
these pics are not from my truck but someone gave them to me when i was cuttin mine.
Heres a good pic of where to cut the firewall.
the sides are pretty easy....once you got the carpet out you will see a small V shape indention in the floor real close to the door that runs the length of the cab. I used that line for my cuts on the sides.
Then the back wall i went a few inches up and cut a section from the back wall the amount of the BD.
Hope those helped!