The bottem part for the cover of my calalytic converter fill off i would like to know if it needs to be welded back on of can i use some type of glue.

 

So just the shield fell off? The converter is still fully intact? If so, I wouldn't worry about it.

 

A cat reaches extremely high tempertures and can ignite material it contacts. What fell off sounds like the heat shield. If you are certain it will never contact anything flammable - well and good. Otherwise, I would replace it.

 

just drill you some holes in that thing go to your local co-op or tractor supply and get you some bailing wire and tie that thing up and bam you're done.