NEW FORUM SOFTWARE UPGRADE COMING SOON!
Perhaps this will help, from Arthur Pirkles book on the '66, '73 and '76 which is chock full of detail. All black and white, no pics, but great info and super inexpensive. After I got an original '92, I got his book for that, too.
Well I couldn't find it the first time, but I did this time. Rifle (4 piece rod): 7 1/2 to 7 3/4" deep by 5/8 to 3/4" diameter. Midline is 1 9/16 to 1 3/4" below the top. Carbine (3 piece rod): same size, midline 2 2/32 to 2 1/4" below the top of buttstock.