Floor pan to kick panel Union?

[custom10nut]

Today I really tore into my truck to find out what kind of patching I need to do the repair the rust.
I already posted abou what I’m doing to fix my Rocker Panels, and will update that thread with pictures.
My question is this:
Where the Floorpan meets the bottom of the kick panels,
How is this attached? Are they welded together, or tacked together and then sealed with seam sealer (Which it appears to be)?
My plan is to cut out the old, fab patches, and Buttweld them in, but I need to know about securing the bottom part.
Thanks is advance