I`ve got an 89 longbed 4wd. 4.0. Here's the deal...
I had almost no compression in 2 and 5 was dead. I got a good deal on a head from an 88 that was completely refurbished but never installed so I snagged it up. Took my old head off on Sat morning, lower end seemed to be ok. I went out this afternoon to put the new head in. Compared them to each other and well... they're different. Got the numbers. My old head is a 2686 (I thought it was 2688 but aparently those don't exsist) My new head is a 3661. All the research I've done says mine came from an 88 YJ 4.2 CARBURETED!!!
Here are all the head numbers I could find in no particular order
New Head Numbers: 3661 F NH-1 88 C29
Exsisting Head Numbers: 2686 90 NH-2 E08 CN
So my simple question to you fine folks is should I just try to sell this one and get what I need, is there a not so hard way to make it work, or does it provide me the possibility of some sort of upgrade?
My initial thought is sell and buy again, but I thought it was worth an ask.
Thanks for your knowledge and time,
Mack