This is a map of Siege of Tobruk, as defended by the 9th Division, from April to November, 1941. You can see the both the Red and Blue lines as well as post numbers and dispositions of the Royal Horse Artillery guns.
Post R49, as discussed in the previous article "Post R49 Tobruk Explained" is located on the Red Line to the east of the El-Adem road. The locations of major battles is also shown.
Click on the image to expand it.
Read "Post R49 Tobruk Explained" here: http://9thdivvy.blogspot.com/2008/07/image-german-aerial-image-of-post-r49.html
image from "The War, The Whores and the Afrika Korps". by NX34089 Cpl. Jack Barber, 2/17th Infantry Battalion, 1997, Kangaroo Press, Sydney.