I missed a 5, the high number is 55310200.
With this clarified: is it possible to combine "msgID" and "Old Posts" into one field, with post 51904009 being the first one to go to "msgID" and anything lower than that going to "Old Posts"? That would be much better than having to explain the difference.
Just did!
Now both scripts oldposts and msgID are combined in the same input box.
I made a few tests and it looks ok. Tell me if you notice any bug.
This was quite easy to do, I can help you with similar demands if you need.