He is boxing not fish plating. Boxing will not, in itself, cause stress risers. Splicing a frame using fish plate is another issue. Not to be confused here.
So Montana, are you closing in the C channel open side to make a "BOX" or something else?
It is probably better not to run a long bead the whole way on the C channel legs.
POST PICS of the issue and area.
What is meant by "outer frame rail" as opposed to "frame rail"? A "C" channel has one web and two legs.
Pictures added.
As it stands now I'll need to weld a plate on the inside to close the C into a box in order to attach the 4 link bracket.
Sorry my terminology, by outside id have to attach this bracket on the flat face, solid side of the current 'C'
