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.