Thanks for the reply. I have 4 and 5, but can't find my 3 install disk. One of my clients needs the source file in 3. They should just buy 5.
Yes, you can! But you need Captivate 3 installed in your computer.
First, open the project in Captivate 4. Copy all the slides. Open a new project in Captivate 3. Paste all the slides.
I have done this with Captivate 4 to Captivate 2, so I am sure it should work with 3.