Aloha Bruce!
You are running into the same problem that hung me up for several years. All of our planes are actually already on the AML for the Air/Oil Separator. As mentioned, several members provided me with copies of their 337s, but my IA is… um…, well… “finicky” (not the adjective I would use if we were together) about such things. It was listed under the former TC holder, Prop-Jets, INC on the AML the whole time. The 200, 200A, 200B, 200C, and 200D are all included on the AML. I know that you are an A&P and I think IA? The AML paperwork arrives with the hardware for the logbooks. The person at Airwolf that finally broke the code for me is Logan Simmons. He can be reached at: Phone: (918) 561-8696 or Email: logans@airwolf.com
What you want to order is the AFC-W302-A kit with the W-3014 Air Separator Assembly if you have the wet vane vacuum pump. The Garwin G200 that Mr Grouleff mentions earlier comes off with this configuration. It is my understanding that these G200s can be sold for a nice sum on the internet as more folks are returning to the wet vane systems. I purchased my Airwolf directly from the factory. Aircraft Spruce has them as well. Same prices. You can call me at (337) 263-0127 if you have any questions too long to type. I’m central time; know that yours changes.