Ford 5000 Flywheel Installation

[Tractor5000]

I was doing a clutch job and removed the flywheel to have it resurfaced. I didn't even think about marking it before removing.
I have a service manual and it talks about it can only go on one way, but I don see any key or anything else that would keep me from putting it on anyway I want.
Can anyone help me?

 

[joecdeere]

the bolt pattern will only allow it to be in one position