Go point Turbo, I wasn't even thinking.. to much cheeching lol.

OP did you just torque the bolts or did you take at least three bolts off then stick a pry bar or a big screw driver and see if there is a crack by moving the flex plat front and back looking for cracks.. they will crack like in Turbos pic also look for black streaking sometimes thats a tell.. look at this pic.

 

I just backed them out partially and torqued to spec. I didn't pry it at all but I did look for cracks and saw nothing. If it stops raining I'll get back under and wiggle her around a bit.

 

And as far as the engine code goes, it looks like it was a light stamp and I can't really make it out. looks like 804 ^ < (I assume this would be MX) and then I haven't a clue from there.

 

Yeah.. take three out loosen the fourth.. Then pry around front and back looking for cracks.

 

hmmm,, I have no clue.

 

I believe you have a 0630 head. To my knowledge there never was a 0650. 0720 proceeded the 0630 and 0331 was after. Maybe the block is a 2000-2001.

 

I actually just came across this...
"http://www.jeepstrokers.com/forum/viewtopic.php?f=5&t=64
Stock 242 (4.0L):
1987-1988 XJ 173 hp and 220 ft·lb*
1988-1990 XJ 177 hp and 224 ft·lb**
1991-2000 XJ 190 hp and 225 ft·lb***
2000-2006 XJ 193 hp and 231 ft·lb****
*** Very slight variations within these years corresponding to the 0650 head casting, injector changes, fuel pressure and emissions changes"

It definitely reads 0650. I tried taking a picture of it but just couldn't get a clear enough picture to warrant posting.

 

Note from DJ
Head casting number by years.
It is easy to determine what head you have. On the driver’s side, about halfway down the cylinder head between #3 & #4 fuel injector but below the valve cover clean the lip of the head with a rag or solvent if really greasy. With a good light, you can read the casting number of the head.

Head casting number by years
Casting numbers are as follows:
Year............Casting No
1987-90......2686
1991-95......7120
1996-99......0630
2000-01......0331

 

Note from DJ
Block casting Numbers by Year
Year*****Casting No.*****Part No.
1987*****53005535*****83503400
1988-90** 53005535*****83505110
1991*****53008405*****4626155
1992*****53008405*****4638959
1993*****53008405*****4728988
1994-95** 53008405*****4778882
1996-99** 53020569*****4883025
2000-01** 53010449AA***5013166AB