Just to update you guys on the Cherokee:
Over the weekend, I finally got it to shift into ninth. To say I'm not impressed is an understatement.
Basically, you have to be doing over 130 km/h and on a downhill that's fairly steep. As soon as it starts to flatten out, the transmission will shift back to eighth. If it sniffs an uphill, it'll go down to seventh or, under load, down to sixth.
On the good side, if you aren't under load and slowing down on a flat highway to slightly under 80 km/h, it'll stay in seventh the whole way, even with maintenance throttle.