Guttering joiner patchs, questions????

Hi all, took the stainless trim off my 75 dusters guttering and found the joiner patches that fill the gap between the A-pillar gutter and the roof gutter are missing. Will probably have to make some as I want to remove the trim. Seeing the previous owner pulled them off, it doesn't appear that originally they would have been welded in place. Were they just crimped in place? Theres no sign of paint or primer behind them either, so looks like a rust trap to me, plenty of seam sealer I guess?
Should they be welded in? Has anyone else had to do this?