Head swap header info??

I would think you could just buy an aftermarket 4.0 header and install that.

Carl

You need a 4.0 header, the cheapest are on ebay Stainless steel for around 50 bucks, these are just direct rip offs of OEM tube header with the accourdian flange to eliminate the cracking problem on the long tubes.

You then need welding skills or a muffler shop to do your collector pipe, your old one more than likely wont be even close to the header's output. The 4.0 collector pipe (or "down pipe") is on the wrong side and routed differently from the YJ and most likely the CJ.