Yeah, like terry said, I’m not very good at describing this stuff, but, you can get either the plastic plate which bolts to the rear suspension mount, where the car bodyshell mount is currently (I think), then get the plastic wing mounts. I found this method quite fragile as it used rubber bands to attach the wing. Or, use the much better wire wing mount bolted directly to the suspension mount. Both normally turn up on ebay now and then.
By happy coincidence I’ve got a photo of both types.

