Just noticed my 92 Heritage z28 has no wonder bar.

Wanna keep it stock but does this really help alot?

I know they came on 85-90 IROC's. Not the best pic on the IROC.

 

The wonder bar is an IROC-Z specific part.

 

Put factory ones on all my birds with 16-17" wheels. If they help and you can tell, you're way better than I am!
I guess it just helps spread the steering box load and maybe was designed to help something else, I'm not sure.

 

I put one on my 83. It was in great shape at the time.

As far as I could tell, it was just barely over the "just noticeable difference" threshold. Made the car feel tighter, more "solid" and "put together", going over bumps around corners. That was about it. A positive thing, but not at all revolutionary. I have no idea whether it would have kept the frame from cracking. (it did, later; maybe it was already weakened before? iunno)

Not worth getting wrapped up in "originality". It wasn't "original" to 91-92 cars regardless. If "originality" is your thing, put on whatever the hell you want, and take it back off when the day comes (it'll be the same day they serve ice cream in Hell) that "originality", to THAT level, matters, with these cars. That simply IS NOT what these cars are all about.

 

You're looking for an OE wonder bar, not one of the many aftermarket versions?

Here's one that was for sale a couple of years ago. Same member listed back in 2016, too. Neither of his threads have said "sold," so it might still be available, you never know.
Iroc z Wonder bar - Third Generation F-Body Message Boards

And here's one on ebay right now.
82-92 CAMARO Z28 Iroc 23s oem wonder bar steering brace | eBay

I installed an OE bar on my Formula about 15 years ago; got it off of a junkyard car. But I'm not seeing a part number on it. Still looks nice, too, so a number should be clearly visible, unless it's hidden on a mounting surface. But I don't see a number on that ebay bar either. Maybe it was labeled with a sticker, like the coil springs were.