6.1 Hemi ECU

Hello: I am a new member to Moparts. I haven't spent a lot of time on this site but I have noticed a lot of people have upgraded an old mopar with a 6.1 L Hemi. I am also currently working on a similar project in my 1973 Barracuda. I have the 6.1 L crate engine and most of the installation parts. My question relates to the placement of the Engine Control Unit (ECU). The Mopar installation sheet recommends inside the car. I was just curious where others have placed the ECU and where the wiring harness passes through the firewall? Any pictures would be great.

Mount it under the dash on the firewall, or glovebox area. Run the wires through a grommet in the trans tunnel, so the bundle of wires will be concealed for the most part

Thanks for the information. How big of a hole did you need to drill in the transmission tunnel?