Is there a page of interchangeable miata parts from other cars, here is what I so far.
Eclipse vents (NA + NB)
Mazda Protege Cam Cover (1.8L NA)
Ford Escort GT Cam Cover (1.8L NA)
Ford Capri Cam Cover (1.6L NA)
VW rabbit fender flares
Ford Explorer side skirts
Which parts do you know of that are interchange with little or no modification?