2'' Square Rubber piece/flap from under chassis?
 

I found a ~ 2 inch square thin rubber piece that had fallen from underneath the truck, 3rd gen 4runner. Looks like it came from under rocker panels but on the inside edge, underneath the truck. It looks like it was for some kind of flap covering a hole. Does anyone know what these are for? And how I should put it back or if I should seal up the hole? I think the Krown rust proofing ate through whatever was holding it.

Need to post a pic......or folks will just be guessing.

One pic of rubber that fell off, the other of flap thing where it presumably fell from

https://cimg8.ibsrv.net/gimg/www.yot...53cb0badd1.jpg

under rocker panel 3rd gen t4r


https://cimg0.ibsrv.net/gimg/www.yot...60f29e312b.jpg

rubber square from under rocker panel 3rd gen t4r

There seems to be at least 3 finger sized holes, drivers side, which were at one point covered up by these rubber flaps. Haven't looked at passenger side. Thinking of just plugging with plastic plugs. It's been krowned inside so i don't think rust will be an issue if I close it up. Thoughts?

Humm, I have not really seen that but I will have a look at mine. I also use Krown rustproofing...

Update:

There are 3 holes on driver side, 3 holes on passenger. I've since plugged them up with some rubber plugs and RTV. I krowned inside the rockers before I sealed up the holes.

I noticed there are weep holes all along where the underside and outside sheet metal are joined together, this is where the excess krown ends up seeping out slowly.

Still not sure what the flaps were for, unless it was a way for Toyota to do rustproofing in there. In any case, I have additional access holes done my Krown guy, so sealing up the 6 seemed like the most logical solution.