In 1997-1999 the 4.0 TJs came with distributors. In 2000 they switched to coil packs and a camshaft synchronizer. That carried on until 2004, and then in 2005 they switched to the infamous OPDA.
Some people have asked about block interchangeability, as well as swapping a distributor or camshaft synchronizer from an earlier model into a later model TJ.
The tone wheel on the 2005 and 2006 models is different. The 2005 and 2006 computer will not work with the prior years due to the different pulse patterns.
However, if you match the OPDA, distributor, or synchronizer to the computer you have, they will all fit in any 4.0 block.
A good example of this would be that you could install an OPDA in a 2003 block (no idea why you'd want to, but you could) and it will bolt-in just fine, you just need to make sure you have the wiring and computer from that 2005-2006 OPDA equipped 4.0.
Exceptions
You can swap a 2005 block back into a 1999 and use the distributor as long as you have the right wiring harness and computer for the distributor. However, the only thing that stops you from going the other way (a block from a 1999 into a 2005 with an OPDA and coil packs) is the bosses are not on the motor to mount the coil rail.
Some people have asked about block interchangeability, as well as swapping a distributor or camshaft synchronizer from an earlier model into a later model TJ.
The tone wheel on the 2005 and 2006 models is different. The 2005 and 2006 computer will not work with the prior years due to the different pulse patterns.
However, if you match the OPDA, distributor, or synchronizer to the computer you have, they will all fit in any 4.0 block.
A good example of this would be that you could install an OPDA in a 2003 block (no idea why you'd want to, but you could) and it will bolt-in just fine, you just need to make sure you have the wiring and computer from that 2005-2006 OPDA equipped 4.0.
Exceptions
You can swap a 2005 block back into a 1999 and use the distributor as long as you have the right wiring harness and computer for the distributor. However, the only thing that stops you from going the other way (a block from a 1999 into a 2005 with an OPDA and coil packs) is the bosses are not on the motor to mount the coil rail.