I own both a Mac ET9640 and a Snap-On MT2500 Scan tools. I am wondering if either of the two 15-pin cables will work for me since they both have OBD-I and OBD-II connectors. I have the tunercat program but I didn't purchase the $100 cable from them. Will the cable from these scan tools work?

 

Try it with Freescan, although I doubt it will work. The Hypertech cable has an OBD I connector but that doesn't mean a thing, the internal structure of the cable wont work without adapting it. These converter boxes used to be available from Andrew, not sure if they still are.