I have a 88 cherokee with 4.0 engine ,auto ,4x4 and my exhaust manifold is cracked what is the easist way to remove this ,do I need to remove the intake and also how do I retrieve the engine trouble codes thks Jeep newbie

I am buying a Jeep this comming week, and I asked my friend (a Jeep Mechanic) what kinds of things to expect.
The cracked manifold was one he mentioned. I don't know how to remove a jeep manifold, sorry.
My friend told me that he welds the crack and they will never crack again. A new one from the dealer is around $600!
I've seen aftermarket for around $400

check this out:

http://www.4wheelerssupply.com/Products_01786/index.html?PHPSESSID=459d0f87c4467025b0706c6de3df9 d5c

http://www.off-road.com/jeep/cherokee/xjproducts/borlaheader/borlaheaders.htm

FredrockinVA