I had some nutserts for the transfer case skid plate that I gave away on here after I got mine. I bought a lot of them when I did mine. I'm pretty sure they were 10mm nutserts. I can't recall the outer diameter of them though. I actually ended up only using it in the frame rail and used flange bolts and flange nuts in the cross member. I also welded the lip of the nutsert to the frame rail to prevent it from spinning, like the factory ones do when you go to remove the skid plate. Fishing bolts into the frame rail for the gas tank skid will be fun. You'll have to pull the rear bumper cover to access the inside of the frame rails. The first one isn't that hard to get to, but after that, you'll need the help of a flexible magnet.
1997 ZJ TSi - 5.2L, 242, ~4" of IRO lift, IRO short arms & adj. TBs, JKS Discos & BPEs, DT3000s, Aussie out back, sliders, OEM skids/hooks/hitch, 31" Duratracs, 15x8 Stealth Crawlers, Niner grille, e-fan, Magnaflow stuff, HO alt, "mean eyes", tinted signals, clear corners, sound system, cloth seats
1994 Caprice - "SQL Lab", HO charging system, SS suspension, show car in progress, some tasteful
2014 Silverado 1500 - DD on order
2010 Terrain - wife's DD, bone stock
2010 Gary Fisher Utopia - Black Ops platform pedals, SRAM X.9 shifters, BB7 calipers/G3 CS discs, NightRider Rebel 3.0 computer
Black Jeep Society