Mixed year parts in engine?

Hello all!

Being new to the JEEP world, I am coming across some wierd findings while replacing the lifters in my 4.0L.
Jeep is a 1999 cherokee sport, the head is the older casting from 1998,( a good thing i'm told), the Valves are from a 2000 part number( lost a keeper and Chrysler told me mine was from a 2000 and newer), and the fuel injection connectors are from a 2001(the ones listed for 1999 are not even close to the ones I have).

I know this by the dealer confirming my findings, they do not match what the Jeep was built with for 1999, and it is from the factory one owner before me ?

Anyone else run into similar?

Hmm interesting. I would wonder about it too. Hope someone can help you get some answers.

Matt would know more about that than anyone I think

I'm almost wondering if someone didn't replace the engine with one out of a JY, maybe a 2000 or 01... then had the head crack issue, or had that issue remedied before the JY purchase with a 98 head and whatever parts that were damaged picked up through sources to get it back up and going.. Almost what it seems like.. Heck could have been an early 99 you got, so the head was from 98 left over stock, then it blew or something, so someone got a newer engine out of the JY, and to remedy the issue with the head crack issues, they swapped the head from the original engine out of the 99 and who knows what really happens for parts wise when you take your rig to a shop or stealership... and they got it back up and running for the PO with whatever parts they could cobble together...