Wren sells them. I believe a Ram 500 case is the same diameter as a Wren 54/70/75/100/SS. Measure your case and check with Wren before ordering. Ron Ballard doesn't show accessories on the Wren USA website but he can probably get one for you. If not you can order from the UK.
http://wrenturbines.co.uk/accessorie...#engine-mounts

Joe