I have just installed a reconditioned 460 engine into my passenger car ( I am in Oz) I was told my engine was internally balanced. I have just discovered my 460 engine was produced after 1979 so it is externally balanced. I have just purchased external counterweight spacer and flywheel. I need to know if the flywheel can only go on 1 way as I am not sure. Does the weight on the flywheel need to be in the same position as the front spacer counterweight? Can anyone help me!!!

 

First of all, welcome to FTE. You'll find a lot of help here!
On your flywheel, the weight, which is part of the casting, will be on the back side of the flywheel, so you will install it with clutch bolted to the flat surface of the flywheel.
The holes are keyed. That is, they are not evenly spaced. You can only install the flywheel one way. You can't mess it up!

Try it, and you'll see what I mean.

Again welcome to FTE, and best of luck!