Regarding intake swap from '89 4.0L. I had heard about swapping from Renix to 2000 intake prior to May '06 issue. I know somebody out there has done this. My query is which header and gasket to use. Appx. 4 yrs ago I was wrench/ service writer at a shop. I had three gaskets sent to me to compare. (renix, H.O., and "horseshoe" intake (1999 up). There are few headers avail as listed by app for '89. I can do swap myself but my ride is daily driver, so I must keep down time to minimum. Which yr app header and gasket should I use with 2000 intake on '89 4.0L? Any info would be greatly appreciated. Paul.  

Probably timewise, effort and money, you would come out ahead if you swaped the complete engine and engine wireing harness. You could pick up an engine for less than a $1000.

The computer for a 2000 would need all the sensors from the original engine in order to run and smog correctly.

The cam is also different between the engines and that would throw off the fuel maps in the newer computer also.

The 2000 has coil on plug ignition, so that is very different.

For a vehicle you need to depend on for transportation and minimal downtime... Don't even think about it!