Look at the brackets themselves. Seen it on a couple where when they make the bends they go a little overboard, and instead of 90 degree bends they are 100 or more.
This closes up the outermost flanges, just enough the arm won't drop in.
Use the old Mark One eyeball or a tape measure to read the opening at the top and where the bends are. Might just need a little BFH persuasion of the flanges to open em up.
97 Sahara, 74 Renegade, 72 CJ5, 55 Willy's (the Beast) Boss 302, 6:34 gearing, Bose 901 speakers.
God I miss that Jeep. Forgot the kinda Jeep, 80 SX4.