from left to right. miata rear, EA82 subaru rear, Miata front, BE Legacy rear (which can also be used...read on)

the key difference, is the upper mount. the subaru ones use a large, rubber bushing in the upper mount. the BE shock is too wide to even fit into the bushing, as well as too short to reach all the way through it.
the miata ones are narrow enough, but still not long enough.
solution? remove the bushing


now, the hole in the upper mount is too large (this is an EA82 upper mount minus the bushing on a miata shock):

so, I went to home depot, and bought a bag of 3/4" flat washers. and sandwiching the upper mount between 4 washers, converted it to a solid mount:

this same method could be used with BE/BH legacy stuff. also, if I had a welder, I'd weld the washers to the mount.....but I think this'll work fine.
full coilovers (tein or the like) for a newer legacies can be used....but a bushing is required because the lower bolt is smaller on the EA82 than the legacy. not so with miata stuff. the lower bushing fits perfectly on the EA82 trailing arm:

finished product:

aftermarket support for NA (chassis code) miatas is virtually endless. so if you can match it with the front (5-lug), you can probably find it for the rear too.
the bad news? Miata shocks have quite a bit less travel. only about 5" compared to the EA82s almost 6.5". and the lengths are a bit less than ideal. at full extension, the Miata rears are about 16" long, and the fronts are about 20" (the same as stock EA82s). I'm using rears here, because I've got the car pretty slammed. but once I go 5-lug, and go to stuff bigger (both wider and taller) tires in there I'll use fronts and only drop the car an inch or so.
also, there isn't a stock spring that'll work easily with this application. so a coilover spring that has it's own upper perch will need to be used. be it cheap ebay ones like I have now, or Ground controls...
I intend to run Ground control springs and KYB AGX shocks all around.
on a side note, I decided to replace the rear brake pads while I had things apart....so I went and bought new pads. while I was driving back from Checker auto parts...I heard a clunk. and when I got home, I found this:
