Disk Utility from Yosemite 10.10.5 (ver 13 (606)) patched to run on El Capitan.
Note: After you have downloaded and unzipped the file, you need to let root:wheel take ownership of the app before the app will run...
sudo chown -R 0:0 ~/Downloads/Disk\ Utility.app
v1 Patching procedure from Restore old Disk Utility in OS X El Capitan, credit @Justus Beyer
v2 Patched with patch pattern from diskUtilityPatch, credit @dimosgmx
Debug menu can be enabled with
defaults write com.apple.DiskUtility DUDebugMenuEnabled 1
Advanced image verification options unlocked with
defaults write com.apple.DiskUtility advanced-image-options 1
To turn off the above options, use the same commands in terminal but type 0 instead of 1.