The bolt holding one of my torsion keys broke and the torsion bar fell off.... Anyone know how to reinstall it?! I've tried and failed....

Do you have to have weight off it?

I think so...

The the main problem is figuring out how to re install the torsion key

Get a 7 ton gear puller or similar tortion key press. Lift front end. Use gear puller to push key towards cab and pull out bolt. Install new. Boom