There are two still on the market that meet the description of what you want one is a Great Planes and the other is the Dubro. Both are sold by Tower. The Dubro is my favorite and normally only use that one but have tried everything that has be avalible for some years and the Dubro remains my favorite as easiest to set up and use.
The one you remember that worked best by adding a spacer shim in the tunnel actually was the early Dubro's however they actually remedied that problem some years ago and its no longer necessary to do as they added a slight molded in spacer. The technique for properly setting up the switch mount charge plug is after the face plate is inserted but before the switch mount is screwed onto the main mount bolt, run the plug that is the charge lead out through the tunnel and then plug the lead that normally goes to the battery (female plug) around to the outside and into the charge lead. You could also use any female plug as this alignment guide. Now these two attached plugs are inserted back into the tunnel and are used to position the pair perfectly before the pinch bolt is tightened onto the charge lead.
John