The only "racing" axles made for w-bodies came from SFPH:
South Florida Pulley Headquarters - Your source for supercharged performance products!

If you watch the video, you'll notice that is Zoomers twin-charged run.

I run 18's on the street without problems. I have the stage 2 zzp axles. I did snap a wbody store axle at the track on 16" DR's a couple years back. I'd guess traction is more likely to break axles than weight.