rear subframe
 

...I've got a complete rear subframe and trailing arm setup already off the car , came with some parts cars I bought...I would like to use it to build my track suspension on....I don't know the year and model , just that they have four lug hubs and brakes...are there any differences between the years for an fc that I should worry about...

Not that I'm aware of other than the hubs. If you are building a track car I would suggest either Mazda competition rubber bushings or going with spherical bearing parts and solid mounts. Poly bushings just bind and don't articulate like they need to for proper grip/response of the rear suspension. Also, delete the rear DTSS bushings with a Delrin replacement which is pretty much mandatory if you want it to be predictable. It's also advisable not to go solid mounts on everything, though. You want a little bit of give somewhere (I chose the Mazdacomp front diff mount to achieve this)