This is similar to mods done for Chevy trucks too. The Jeep shafts are available new (zero miles/wear) from Summit Racing for about $110. I went through this when I was looking to upgrade my dually. Like stated above, Jeep shafts weren't available in the wrecking yards I frequent. 'Used' shafts I found online were going for $60-100...I think both shafts are equal in performance and durability. Very hard to find Jeep shafts here. I also like the look of the Astro ones better. Give me a bit and I'll check on shipping for you.