Kodak made both 80 slide and 140[?] slide Carousel trays. Many non-Kodak companies also make Carousel compatible tray. Most likely they will work on a Carousel, but the only way to know is to try it. Several other projector companies make round trays, but they were not interchangeable with Carousel trays.
On eBay some sellers claim that AIREQUIPT Rotary Slide Trays will work on Carousel projectors, but I do not know.