83mm deep externally, take about 2mm off for the sheet metal and another 3-5mm as the rails are inset. Sooooo about 76mm-ish. n the RackBrute 6U bottom rack. I know, exact measurements would be good. I'm going to go to a store on monday, so I'll take my tape measure with me and pretend I'm not using a eurocard frame I paid 30 bucks for, and am interested in buying a RackBrute.
Oh a suggestion regarding Arturia's foray into the modular world, how about making just the busboards from the RackBrutes available? I have to admit, the RackBrute announcements are what finally pushed me to make a move on modular synths (after years of talking about it), with the idea I'd get a 6U, but after some research realised that I can make a case for so much cheaper with the most expensive bit being the busboard. If Arturia was selling them independently, I'd have bought one instead of the Tiptop µZeus.
After the busboard, how about a Steiner-Parker Multi-mode filter module? I know there is at least on out there already, but the Arturia module could have a "Brute Factor" knob!