ppm output from rx701 or rx704.

I read with interest the several posts regarding rx. However I am not clear on the answers given. So.....which of the two rx (701 and 704) are ppm. I am slow on catching up buy will fit one of these rx to my F450 Quad. Would like to use serial but have Naza M Lite FC which doesnt do serial. never mind. I appreciate if you can help me.
Peter