I did it on a 70 cuda with a 340. I had to disconnect the passenger side header. There is also a plug behind the motor mount. If you need to access that one (I didn't), you would need to remove the mount. You could lift the engine with a hoist, just enough to remove the mount without removing the engine. Again, I did this on a 70 Cuda, I assume that it is the same for a Challenger.....
Note: When installing you could use a socket close to the size of the plug. It will make it go in more evenly when tapping it in.........
