Glad to help, Al. Also, I have a Sams Photofact and copies of a Scott Service Bulletin and owners manual for the Scott 335 should anyone need them.
Goofyfoot, look here at the Berner's Site for MR 65 or MR 65A. This shows a MA 5 adapter that is mounted to the chassis of those tuners, and appears to work with them only. Also, the MR 65B is a stereo tuner. The MA 6 is shown on the MR 66 page, and appears that it only works with that tuner since it is powered through a 4 pin plug on the back of the tuner.
So, to answer your question, all multiplex adapters are not compatible, although it appears that the Mac tuners may work with the Scott and Fisher adapters.