First and foremost, my exhaust. I ordered a Pacesetter exhaust, headers back. After ordering it, but prior to receiving it, I removed my rat's nest and began to remove my stock exhaust. Well, it turns out that Pacesetter only makes the headers anymore, but not the rest of the exhaust. Can I just pipe it back from the headers and throw a muffler on?

Secondly, I've got some major rust on the back quarter panels. Big surprise, right? I have found a cheap '82 in my town for a decent price. Do the rear quarters match up so that I can just cut them off and weld them onto my '79?

Also, this '82 I found has a 12A. I was under the impression Mazda switched to 13B in '81. Was this not necessarily the case?

 

Only the GSL-SE models (only made in 84-85) came with the 13B's

 

think you'll find that universally around the Forum most regard PaceSetter system as crap. Racing Beat (for one example) offers far superior design, construction, durability and performance. And you can get everything for a 12A system. get what you pay for....
you can tie it into the factory exhaust but you will be getting little of the performance you expect out of a correct, complete system. Stock muffler is a big inhibitor to allowing the free breathing a header need to deliver the Goods. Thus the Power Pulse muffler from RB does the job with their header combo.

Rust panels: depending how much replacement metal you need, the later FB RX7 panels will work UP TO THE BUMPER AREA. SA-FB bumpers are different so metal shape is too.

Alternate:
This guy _manufactures_ replacement panels, ready to go:
Stephen@sbrooks43.orangehome.co.uk

Steve makes separate panels for:
-rear behind rear wheel
-wheel arch
-metal in FRONT of rear wheel
each avai separately...
Quality pieces-

Stu Aull
80GS
Alaska