Sam, I need the
ECM from a Cherokee\equiv that had the optional 45RFE trans - those vehicles will have had the separate TCM and harness, so the ECM will have been conversant with the TCM - and the TCM and harness would be required, also - voltage and resistive input sensors are easily duplicated, switches and frequency sources are easy, output control\feedback is easily duplicated with surplus-cheap adjustable time-delay relays, etc - I can kludge-up a test set that will totally convince the ECM and TCM that they are in a running vehicle, with varying loading at varying speeds with varying demand, just as if it was from a real nut behind the wheel.
BTW, folks - I'm not asking for donations, here - locate it, name a price, and sheckels will cross palms upon agreement.
The main differences in the 545RFE and the 68RFE, other than the altered planetary ratios to achieve the 6 speeds, is the increased shaft diameters, the number of clutches in each drum, the number of planet-gears in each planetary set in the 68 - everything else is same - the 68 TCC is 13" dia vs 11"dia for the 545, much huger and deeper, as the Cummins uses a deeply-recessed flexplate for their convertors - thus, there is no real estate in the KJ floorpan for the large 68 bellhousing - other than bigger is better, the really main difference is the firmware in the TCM - altered pressures, altered clutch-apply times and volumes, shift vs load patterns in selectable normal and tow mode, TCC lockup function for the Jake Brake - you name it, they got it, we didn't - who knew?
Could pull the guts from the 68 and install them in the 545 to get 6 speeds, but, due to shaft diameter increases, would require massive work in the TCC, massive work in the mini-241 transfer case (or use the 241-242 from the big Dodges, all new yokes\driveshafts - TCM firmware is the big holdup, unless someone has broken the code - you'd just have a Godzilla trans with a Gecko personality.
The HDMST - heavy duty multi speed transmission, 4, 5, and 6speed = 45, 545, 68 - has been a top-option upgrade, and standard equipment, in several Jeep and Dodge and Chrysler lines since '98 - those early versions all required external TCM, interfaced to the Mitsubishi-based ECM - later version control was incorporated in the Mistubishi-based PCM, losing the external TCM - the KJ CRD has a Bosch ECM, requiring the external TCM - the trans hardware is similar, with TCM firmware allowing 4 or 5 speeds in the early versions, or 6 speeds in the 68 version, but the Mitsu or Bosch interface is the as-yet unscalable wall.
TCM and ECM connection is WYSIWYG, just like connecting your keyboard, monitor, printer, and internet link to the PC - easy to connect, easy to trace, fairly easy to diagnose - what you don't see is all the intercommunication over several different busses to and from those user-friendly devices, not even easy to interpret and diagnose, even with a schematic - same with the six wires in the harness for the vehicle intra-net -
CAN, SCI\K, PCI - ECM converses with the TCM on the SCI\K and PCI buss links, which is a problem at incidence of upgrade, and is the problem with improving KJ response.
So, I'm wanting to look at the various version(s) to get a sense of direction(s) - may require the PCS solution, but I need a better understanding of the V\T clutch-apply schemes with respect to torque management request - and lots of other stuff, incl what can I live without when transplanting the '07 68RFE into my NOBD '96 Dodge CTD truck
BTW - that '07 68RFE trans currently resides on the floor in my den - it's shiny new clean, and so mechanically and esthetically purty, I might not even mind if the transplant problems are unsurmountable, and I just use it for conversation piece, placed under a glass-top coffee table..................

Additionally the ZJ never used the 45RFE, however did use the 42/44/46RE and the 46RH.
Also, since the cherokee uses a CCD bus I think you will find it much easyer to use ZJ components that use the PCI bus. I've been looking into the XJ CCD bus and its a problem for compatiblity with the PCI bus components.