You ACG masters may be well aware of these products, but I discovered them recently, and they work great. I purchased my first link coupler type rolling stock and locos recently. By chance I stumbled across Stuart Baugher and his web page soon after....
http://www.adaptercoupler.com/
I was having trouble with several link couplers staying coupled plus I wanted to intermingle them with my knuckle coupler stock. So I purchased a supply of Stuart's latches and his link to knuckle adapters (he sells a number of other coupler/connection related products as well). I know I could have modified or replaced couplers, but this was a very simple and very inexpensive solution that works. Both products have performed flawlessly in the few months that I have been using them.
By the way, when he called me about my order, he said he is looking for people who want to test a product he has developed for doubleheading ACG steamers.