Your fender welt starts at the top of the fender and the splash apron where you had the big gap and runs down between the two pieces to the corner where the fender, splash apron and the running board meet in that corner. Cut some slots or V's in the welting where you think the bolts are going to go through to bolt the fender to the splash apron. Slide the welting in the gap, push down on the bead to seat it in place then tighten up the bolts enough so that the welting is snug but not too tight. With your pliers pull the welting down so it is snug in the crack and tighten one or two bolts, I usually push on the bead down as to tighten a bolt so the bead doesn't pop up. Now, pull the welting down to the corner and push the bead and all the way through the corner where the splash apron, fender and running board meet until you can get pliers to grab it underneath and pull tight. As you will see the welting does not cross the running board at the fender as the 30's do. When you go back and tighten your fender bolts make sure the bead is still pressed evenly on the crack for neatness. When it is all bolted up, there will excess welting exposed underneath, you can trim all that off up to about a quarter of an inch to the metal which will look neater.
