Hey Okie,
Sure, weld it. But that's what I do for a living, so let me speculate. The thing has enough stress in its life that the factory-specs allowed it to crack repeatedly. You really think that welding it and creating a dramatic increase in stress and a new HAZ is going to be a durable fix? I think the point we are making is that it is a common Jeep failure for this era XJ. Why should scads of people resort to buying a new one every handful of years? I have an '87 XJ and the exhaust STILL hasn't cracked after 285,000 miles. But the manifold on my '90 that just turned 100,000 is about to go on its third one!!!
Besides, if I am going to bother the disassembly to prep and weld, I will fork the cash down for a header at this point.
OK, I will stop being a baby about it. I just had to make a point.
-Rich