Personally I'd go newer if available. TJ's use different cams but it's usually not a problem.
And yes, all 2.5L blocks should be date coded on the driver side. Not sure what MR Ramdom is thinking with his passenger side exhaust manifold...
I LOVE being dyslexic... I specifically told myself to say driver side, but both times I put down passenger side.... I even edited the post, thinking I was correcting it, and put passenger! Ugh...
I think there are at least three different cams, if not four. 87-90 era didn't have as much overlap (EGR was eliminated on later models due to more overlap), 91-95(6) I think had more duration than 97-2001(2?)... There might have been a cam change in 00, some other odd internal things changed then too. I'm fairly certain that the earlier cams would at least make the engine run smoother, if not give a little more power. Also, the compression ratio was bumped down a little in 91... Valve and timing chain covers were also changed between the three years (I believe)
If you're planning a rebuild, then in my opinion it doesn't matter what year you choose... If you're just swapping in a newer motor sans rebuild, heed jeffy's advice.
