I had cat stolen from my 95 Tacoma 4x4 four years ago. Not fun at all. After installing a new converter I ended up with adding custom made shell/skid plate which completely covers this "precious piece of equipment" from thieves.
After I got 2012 4Runner I found that there are two converters exposed with no protection at all. I was not happy with that at all. I was looking for some similar protection I had in my Tacoma and the closest I could get was OR-FAB Skid Plate / Cat Theft 05-14 Toyota Tacoma 6 Lug Trucks ONLY. OR-FAB did not have such skid for 4Runner and they could not confirm it will fit but I decided to give it a try. I measured both frames under the transmission and it was close enough.
I got the skid of ebay for $156.60 no tax, free UPS shipping. I ordered it on August 15, the skid arrived 5 days later. Not bad at all. The box was huge
Inside the skid was well packed and protected from "UPS guy" with foil and sprayed-on foam.
Now trying the skid on my 4Runner I found that it is not direct fit, but quite close.
1. Brackets holding cross-member under the transmission in my 4Runner are kind of sticking out (hanging lower than cross-member) so I had to trim the sides of the skid by exactly 1 inch. Super easy with angular grinder and metal cutting wheel.
2. Original holes for mounting a skid to a cross-member under the transmission do not have corresponding holes in my 4Runner. However there are two M8 threaded holes on my 4Runner on each side of cross-member. I decided to use these holes form skid mounting. I drilled two additional 8.5mm holes in OR-FAB skid plate. No big deal either.
These are all modifications for skid I had to do. Modified OR-FAB skid plate shown on the picture below.
And now it is mounted under the car.
For this picture I used some M8 bolts I have laying around, but they are replaced with stainless steel button cap bolts with hex key.
The front mounting holes in my 4Runner are exactly in the same spot as in Tacoma frame. I just followed OR-FAB instruction.
But there is a "gotcha" - factory front skid plate in 4Runner is different than in Tacoma. In Tacoma the center of front cross-member is exposed, so OR-FAB skid fits perfectly. In 4Runner the entire cross-member is covered with skid plate and there is an extension plate bolted to it.
That portion of factory skid plate is not needed anymore so I cut off both brackets used to mount the extension. Additionally one of the holes in cross-member that OR-FAB skid is using it is used for hook sticking up of factory skid plate. It was also cut off.
Now the OR-FAB skid front mounting screws are covered with stock skid plate.
It is possible to use most outer holes in transmission cross-member using original OR-FAB hardware but I would have to shorten bars which are welded to OR-FAB nuts and use my own over-sized washers under the bolt as holes in skid plate are quite big. On this picture you can see why I had to cut off corners from OR-FAB skid plate
Now both converters are not visible and not accessible to vandals - from the bottom and from both sides.
In order to get to them a thieve will have to have two different hex keys and 12mm socket required to remove two skid plates (total 8 bolts). I believe they will find it to difficult and not worth the trouble. I hope I'm right.
The only inconvenience of having that skid is that it has to be removed for greasing front shaft - oh boy, a little bit more work every 5k service.