Only one company ever made specific headers for the 78-87 G body cars with Stratostreak V8s, but they folded many years ago. You could advertise in the wanted section here to see if anyone has a used set hanging around. Indian Adventures is the company that used to sell them.
The RA III manifolds do allegedly work also, but right now they're pretty scarce, and expensive if you find a set.
I seem to remember that the universal 3 tube D port headers also fit a late G body, they're fairly easy to come up with, new or used.
Link to Hedman 3 tube headers:
https://www.summitracing.com/parts/h...0/make/pontiac
There are also the shorty headers that mimic the RA III cast iron manifolds, but they're priced pretty hefty to buy new:
Link to shorty headers:
https://www.summitracing.com/parts/h...0/make/pontiac
I hope something here helps you out.........
