In the future you might want to use a bit of punctuation because it's really hard for people who might answer your question to even figure out what the question is saying not to mention general legibility of words not that we have to be English professors here but at least a little bit of normal sentences that are a decent length and not totally run on like the one I'm joking you on would be extremely helpful so just something to keep in mind for the future...
Now, to answer your question: Rubber will not work - I'm not even sure how you might attempt to use rubber. You can rivet some sheet metal over the hole if you want a quick stop gap measure that will most likely continue to rust. If you want to repair it correctly, cut out the rusted metal and weld a patch into place, then prime and paint the inside and prime and undercoat the bottom.
Visit my repair page for Repair info, with pictures!
http://home.dencity.com/mustangcub