I made the one Universal rivet a flush rivet per advice on line.
My double flush rivets didn't look like double flushes. But they are lower than the others with dimples. I countersunk, but not too much because the material is thin. Plus I examined this area under the main gear weld mount and these will work. I used a 3.5 length rivet instead of a -4 or -4.5 to keep the shop head down in the countersink and down away from the weldmount.
