I have a 94 cherokee sport 4x4 I6 4.0 engine, i noticed that its leaking coolant and i noticed its from one of the 4 block freeze plugs the one right behind the exhaust. Would it be hard to change them or would it be better to take it to a shop? any idea how much a shop might charge me?

 

This depends on your mechanical background, there easy to change its just a ***** to get at some times.

 

Not that hard!
I'd pull the intake and header, replace all the freeze plugs on the side and fix the crack in the header at the same time.