The Hemi 6 controller from MSD can work both 5.7 and 6.1. There is a jumper loop in the harness that you either leave in tact or cut, depending on engine. The instructions are available on line from MSD. I know this works for a fact. I am running a Hemi 6 controller in a 5.7 right now that was previously used on a twin turbo 6.1 Jeep.