I have a 79 and just got a full exhaust off of a 83 for a good price. Will the Racing Beat headers that came with it work? I haven’t been able to find good information. The flanges should be the same right? If there’s a difference please let me know what it is

 

header should bolt up just fine. not sure how different, if any, the rest of the system is between SA and FB.

 

You may need to fab up some hangers at the back before it goes over the axle, 83 was hung a bit different from an SA I think.

 

Yes different hangers and the midpipe you have to re-use before the muffler on a "street exhaust" is different.
I had to cut and weld mine to have it working.

I ordered an FB exhaust as I have an 81 FB ... to discover that in France Mazda kept the same exhaust as the SA until 83.