I built my own slide out tray for the Kohler in my Classic, following Bkahler's lead.
I got my 20" 500lb slides from a guy on Ebay... I paid $50 for the pair.
Not sure on the config of your later MH, but the following pics might give you some ideas.
The Kohler is a twin cylinder, and is mounted on its own plate... I just added the slides and a piece of angle iron, lifting the unit up about 1". I only need to undo the 2 exhaust clamps and drop the muffler, then with a little cable watching, the whole thing pulls out.
At least I can now reach the rear spark plug..