Stop in for a cup of coffee

Question, How the heck do they run a 5.7 or 6.1 or 6.4 on a Dyno? What controls do they use?
depends. most modern dynos have computer programs that they simply plug a universal harness into the engine harness. That's how the Mustang Dyno we had at TST worked any way. Just selected the program from the menu. Course each manufacturer you had to pay a yearly fee for it or use a universal software. Chrysler DTRB software was nearly 800 a year.