Late '80s - early '90s F bodies (Camaro/ Firebird) Z28, IROC, Trans Am. They come in different sizes, 36mm is the largest. Moog makes bushings to install on the G body.
Hit up the yards. I scored 3 in one day at my local yard a few months back. $40 total or so for all...Woo Hoo! If you can read it, the bar diameter is molded into the sway bar frame bushings (gm only bushings, may be hard to read, bring brake kleen). HTH!
The last one I scored still had the part number and code label on it. But it's very easy to mistake the 36mm for the 34mm bar. Measure it before you pull it. What I do is take a Crescent wrench and open the jaws at the center of the bar. Than take a tape measure and see what it reads. BTW the hollow bars only came on 3rd gen Camarobirds that came from the factory with 16" tires. In other words don't waste your time looking in the V-6 powered cars.
Have you seen this sticky at the top of this forum? It has all the parts you could ever find in the junkyard including the 36mm and 34mm sway bar donor cars...