I am actually considering milling a slot in my chassis even though I have risers. There is plenty of space under the main body of the diff but not under the higher part. It would feel better to have a slot under there just in case a stone tries to get under. But as it is stones get pushed to the side and clear under the diff anyway... so it´s no biggie. It´s most a matter of me being too lazy to unscrew everything from the chassis... I might dremel from underneath though but I dont know how pretty that would look in the end...

Stefan