Measurements In Inches: Chassis Dimensions: Depth
(Rear Panel to Front Face of Power supply) = 7 3/8 Height
(not including rubber feet) = 5 1/4 Width
(no handle) = 12 3/8
(what you refer to in your post as "length")
Handle + 1.5 inches, therefore...
Width (with handle) = 13 7/8
The Rubber feet add 1/4 inch and are on both the bottom and the "end" (opposite the handle)
So the rubber feet also add 1/4 inch to the "height" and the "width".
If I were designing a home for my new 6B I would I would keep the bottom feet since there are vents underneath the unit. The end ones require removal of the power supply
to access. They are secured from the inside (a design flaw imho, especially since they have a tendency to come loose.)
Finally the depth of course will vary based on the modules installed and how far your various new cool 500 series module stick out!