Hi TWXadmin,
Referring to the gitbackup extension, as its (main) developer, I'm unclear why you report the diff widget is not available.
I'm running the extension in my 9.3.8 instance and I can see the widget in Mashup Builder - also it works well in the GitBackup.Main.Mashup
As a reminder to others, even if in this situation we speak about a widget that is part of the extension and not meant for custom use, if you have any issues with the GitBackup extension, please report them here: https://github.com/PTCInc/thingworx-gitbackup-extension/issues as it's not a PTC Supported product.