Spencer_P

I've got a 4.0 that I was told came out of a 96 Cherokee. I'm hoping someone can help confirm what it came out of because I am finding conflicting info.
It has a 0630 head which I believe could be 96-99, but the block PN is 53010449AA which from what I've found is the 2000-2001 PN. The block also has XL667408 and 905MX20 stamped into it, which again from what I've found the second code means it was built in 99, which I guess could be the case if it was installed into a 2000?
The engine has the same PS pump and belt tensioner as both of my 96s which I thought was a 96 only thing but I could be wrong on that.
Another clue is that the engine in question has the more rounded intake manifold which I believe came on newer 4.0s, however, it does have a distributer.
Any help is appreciated!

cruiser54

905MX20


4.0 Engine date codes

The date code is on the passenger side of the engine, on the block, just forward and up from the distributor on a machined flat surface.

The digits of the code identify:
 1st Digit-The year (8 = 1998).
 2nd & 3rd Digits-The month (01 - 12).
 4th & 5th Digits-The engine type/fuel system/compression ratio (MX = A 4.0 Liter (242 CID) 8.7:1 compression ratio engine with a multi-point fuel injection system).
 6th & 7th Digits-The day of engine build (01 - 31).
1. FOR EXAMPLE: Code * 801MX12 * identifies a 4.0 Liter (242 CID) engine with a multi-point fuel injection system, 8.7:1 compression ratio and built on January 12, 1998.


May 20, 1999

Spencer_P

Thanks!
Is there any reason it will not work in a 96?

cruiser54

Not one.

Spencer_P

Good morning, I've got a few follow up questions:
1. Comparing PNs from 96 to 99 the only difference I noticed was in the distributor rotor. Should I get the 99 one in place of the 96 one I purchased?
2. How should I go about adding the temp sender that would be on the back of the head since the 99 does not have the threaded hole?
3. This question is regarding the 96 engine that is being replaced, it has just shy of 200k miles. The rocker arms all have an X stamped onto them, and IMO the top end looks pretty good for the mileage, is this indicative of this head having past work done? The service history makes no note of any engine work and does show that for the majority of its life, it was maintained so it could just be clean, but not sure what the X means.

Thanks in advance!

Spencer_P

cruiser54

Use whichever rotor fits. I didn't think there was a difference.

These engines looking this good at that mileage is not uncommon at all.

You can drill and tap the head for the sender.