There are small differences like the A/C brackets but it's the same basic 4.0L block.
The '99 Grand Cherokee 4.0L will have the less desirable 0331 head that is prone to cracking as well as a distributor less ignition system. The Grand 4.0L will also have a split/double exhaust manifold design with two upper O2 sensors and third one after the cat. The '99 Cherokee 4.0L will still use a standard distributor with cap, rotor, and plug wires. Also the Cherokee 4.0L from a '99 will have the 0630 head which has a better casting that later 0331 heads. The Cherokee exhaust header will be a one piece unit like a traditional long tube header with a single upstream o2 sensor in the header and then one after the cat.
