I recall reading somewhere that you can tell by what's stamped on the top of the head near the exhaust manifold.
I was able to take a picture, this is on my 2000 XJ.

Thanks, Mike.

 

You most likely have the famous 0331 the number is in the middle head along the valve cover

 

^ what he said...The location on my head is about half way down. From your picture that number is the end/corner which, in this case, is not what you are looking for.

 

That's where it came from. Middlish along valve cover on right

 

There should be another number on there somewhere

 

Sigh, looks like I have my answer.

 

From everything I've read, you were stuck having that head in a 2000, 2001 Cherokee unless a previous owner already replaced it.

 

Yeah, I was hoping the previous owner had replaced it.
It's pretty apparent the engine had over heated before, but I don't see any signs of it going bad, yet.
From what I understand, it's inevitable.

 

Yep, if your heat doesn't work very well and you are losing coolant somewhere, thats where I would look. If all seems well and good. Run it till she breaks. No sense fixing it if it isn't acting up. Just be prepared, it will most likely happen at some point.

 

My heat friggin' sucks.
I am losing coolant, but I think it's through a hose or water pump.
Both have a visible leak. Once it does start leaking from a crack in the head, how long do I have to fix it til it's ruined? Or once I notice it, do I just tow it so I don't do additional damage?