2 main reasons:I may be missing something... but, what is the benefit to changing a steering shaft? Just for new joints? I dont get it
-No "rag joint" in the design
-Increased header clearance
Technically speaking, both of these are negligible depending on your application. A stiffer intermediate shaft isn't going to fix a worn steering box and tire rod ends, and even a wide Buick V8 with headers can clear a stock intermediate shaft, let alone a small block Chevy. If you've replaced all of your steering components and you still want a more solid feel, and you don't want to buy a new rag joint, then a Jeep/Astro shaft is for you.
I don't mean to sound sour because I know this is a popular move, but I just wasn't too impressed with mine. I switched back to the stock style and it treats me fine at my skill level.