Up for sale is a Hidden Hitch for a Miata by D'Lan. Comes with receiver for ball mount (ball not included- see pics). Works great. I used it for towing a trailer behind my Miata for years without a hitch (ha ha ha yeah I did that). I had this installed on a 2002...so I know it fits NB (99-05) Miatas, I am not sure about NA (90-97) Miatas, so don't ask me. I don't see any reason why it wouldn't work on a NA...but I cannot guarantee fitment. Comes with hardware to install. When installed, it cannot be seen, hince it being called a Hidden Hitch.
$200 shipped