swaping multi track pad from new macbook to old macbook

I've never found an A1181 topcase/keyboard that would not work with another A1181, so if it's from an A1181, it should work on another. If you're talking about a new unibody white MacBook, that will not work, because that has a totally different model topcase/keyboard that will not fit.

Also, in case you're not aware, the topcase, pad, and keyboard are all one single piece, i.e. it is not possible to swap just the pad because it is sealed in plastic and not removable from the topcase and keyboard. It's necessary to replace the whole thing.