The 1999 has the 0630 cylinder head.
The "infamous" 0331 head is on the 00-01 XJ engines.
So there is little chance of getting the 0331 head on any of these engines, but ask to make sure as you do NOT want it.
I have not had any personal experience with any of those companies, but be sure to do your homework if you are ordering from them. Maybe some with some experience will chime in.
Another thing to consider is searching for a salvage yard engine. Plug and play and you're on the road. A very economical way to re-power with minimal investment.
I cannot remember how many salvage yard engines I've installed in 38 years of wrenching, and have only had bad luck one time.
Without data, all you have is an OPINION!
Past Jeeps: '49 ******, '81 Scrambler, '88 Comanche
Current Jeep: 1999 XJ Sport, bone stock, daily driver.
I work on Jeeps!!
Last edited by tjwalker; 01-04-2011 at 06:44 PM.