found a kit for a 80's rx7 on site how hard is it to fit to a 83 body
what are the big differences

conversion 12a to 13b 1 gen
where to buy a wiring harness doing a 82 to 85, ecu not sure what else needed?

 

Are you putting a gsl-se 13b in your 12a car? If so, I have a gsl-se wiring harness (complete) that I would be willing to sell. $250 w/ECU plus shipping james7hull7@hotmail.com

 

79-80 rx7 front and rear bumper are different along with fender (because of front bumper). 81-85 is same. You CAN convert the front bumper (the metal part - actual bumper not the cover) and then the fenders would need replaced. That would work, only you would then have body line issues. I suppose you could shave the body line, but it would be a lot easier to just get the 81-85 kit. Also, if this happens to be a kit from victoria british made by wings west it is currently not available. Same kit is on mazdatrix and not sure of availability. The 79-80 kit is available though.

 

the 79-80 bumpers are like a heavy steel. if they hit something, i dont think it would affect the car in the least. those things are beefy.

 

Actually, no there won't be any body line issues. I think where people get the idea that there are different body lines is that they haven't looked closely at a 79-80. The front fenders are exactly the same except for the very front bit, at the bumper. The 81-85 have a cut straight down from the bumper cut out that is covered by the urethane bumper cover, while the 79-80 doesn't. If you put the late bumper and cover on, there's just an extra bit of metal hidden under the urethane - doesn't hurt anything. I've seen it done on an autocross car before - he wanted the lighter aluminum bumper. The crease that runs above the body molding on 81-85 is actually there on a 79-80 - the body molding is *in* the crease on the early years.
The later body kit will likely fit if you use the later bumper core, assuming that the kit is the type that replaces the whole bumper skin. At worst, you can replace the front fenders and the bumper.

I've removed most of the body molding from my '79. Well, one side, anyway: pics

 

Well, crap - I need to pay attention. He's found an early kit, trying to put it on a late car.
Well, there'll still be no body line issues with putting '79-80 fenders and bumper.
I doubt that the 80 kit will work well with the 83 front end. There's also the matter of the license plate location in the back - 79-80 puts it up high instead of down in the bumper, so there won't be any provision for it on the '80 kit.