So, I made the 60 mile round trip to my dealer today, the one who sold me the trailer 8 years ago and who still services them. I enlisted the lady in the parts department, thinking they had to have had some experience with getting the slideout parts. She ran into the same issues Me and the Makarios rep had. The first Lippert tech rep hung up on her and the second was no help at all. When she called AP Products, they were sympathetic, but, even though the motor was theirs, there were no cross references to the old motor or to Lippert's part numbers. They told her the motor I originally asked for, and was told was wrong, should work. So, now I'm into this for over $500 and still have a broken slideout. Hopefully I'll get some refund when I ship the old motors back. I have to say, this is a lot harder than it should be. I guess, now we're ordering the part from Lippert directly, which will undoubtedly be the same part as the AP Products/Tuson people have on the web, for twice the price.
I guess I should retitle this thread "Why rv'ers look old and grey".