Side note, I can confirm that the transmission from the 2001 Cherokee fits the 1999 Gen 2.5 Montero 3.5L. This is the auto from the 4.0L cherokee.

You have to change the tails haft housing to the montero one, and the pan ,throttle cable, NSS, output shaft speed wheel.. All easy change outs.

You either need your old torque converter or to get a new one - the TQ listed by DACCO at the major parts houses is the wrong one. The pilot is horribly wrong.

The jeep transmissions need the front speed sensor (1998-) in order to work in the Gen 2.5 FYI. Without it your transmission computer will be pissed.