And that's why your 545 may have a 6 on the oem model # tag - it is really a 6-speed transmission, with the 2nd and 2nd prime ratios.
This has all been said before, but I'll nail it all up in one spot for your viewing pleasure - what is needed for upgraded heavy-duty transmission service is the Suncoast torque convertor, the Transgo shiftkit, and an auxilliary cooler, as from Derale, with t-stat controlled cooling fan - also available for you northern guys is a t-stat controlled valve to bypass the external cooler in below 30deg winter temps
The t\c is the greatest source of heat when impeller rpm exceeds turbine rpm, which is anytime the TCC is unlocked - that's the 'moan' you hear as you attempt to increase vehicle speed and engine rpm increases while vehicle speed slowly wallows upward: the t\c clutch has unlocked and the hydraulic coupling is 'slipping' badly - this is addressed by lowering the 'stall' speed, or 'slip', by increasing the vane angles in the impeller and the turbine, or\and increasing the diameter and depth of the impeller and turbine - brazing the vanes also reduces slip by stabilizing the vane blades and maintaining the dimension between the vanes and the housing, thereby reducing leakage.
The oem flexible plastic stator is replaced with a rigid aluminum unit with steel-cage sprag, and the various plastic bearings are replaced with Timken needle bearings
The TCC clutch gets improved friction surfaces and increased surface area (some vendors mention Kevlar), improved apply-piston seals and enlarged passages which improve lockup and reduce interval between apply command and actual lockup, and release command to total release.
A "billet" housing cover reduces housing flex and resultant clutch drive-surface flex, which reduces slip during lockup.
Shifting interval is next greatest source of heat, where the valve-body accumulators are 'programmed' to increase the delay out of the current range and into the next range - this isn't even good for the clutch friction surfaces, so the programmed-in slip generates much additional heat - you can also do something about this by installing a shift kit.
The TCM controls the shifted range: 1-2-2'-3-4-5, but has nothing to do with this aspect of shifting - this 'programming' is done in the valve body by the mechanical engineers, using soft springs, small orifices, leaks, and other sneaky tricks of the trade, all designed to protect the transmission during the warranty period - any good shift kit 'reprograms' the valve body by increasing and\or decreasing spring tension, opening up orifice diameters, using improved sealing ring compounds, etc - result is firm, quick shifts, reducing heat.
Transmision cooler capacity - size and location - is also responsible for added heat by not providing adequate heat exchanger surface area, or by placing the cooler in a previously heated area, such as the engine coolant radiator, or in combination with other air-over heat-exchanger.
B&M, DeRale, Hayden, and many others offer external auxilliary transmission coolers you can install yourself - as the little Jeep is slightly taxed for available real estate, an auxilliary cooler module with built-in cooling fan becomes very attractive, in spite of the increased cost - these often can be 'self-engineered' for way less than the commercially available models
So, there you have it in a nutshell - tho, a further word about shift kits is necessary, B4 I get off my soapbox
I've been doing this stuff many years across two centuries, racking up lots of experience with all systems automotive, incl automatic transmissions, torque convertors, and shift kit improvements.
Here's a little tip fer ya that still has me flabbergasted: Transgo has always offered a basic shift kit with minimal items to effect a basic upgrade, functional but basic - for those with enhanced sense of thrill and heavier right foot, they offered a transmission reprogramming kit, with all sorts of extra goodies intended for really hi-performance service, naturally more expensive with the pre-tuned valve-body separator plate and other required hard parts.
For your CRD, the Transgo SK45RFE shift improver kit has the prerequisite springs, rings, o-rings, and thicker accumulator cover plate to improve shift quality, and is very reasonable in price at around 45bucks.
The Transgo 45RFE-HD2 Reprogramming kit is a stunner, tho, at greater than twice the price, with only addition of 1@ $0.10 1/2watt carbon film resistor and 2 additional servo springs - all at around 109bucks - bummer, impo.
Fortunately, guys'n'gals, relief is at hand - ya see, Suncoast not only offers the greatly improved torque convertor solution - the 545RFE-CRD-1 at ~700bucks - but also the Transgo 45RFE-HD2 reprogramming kit at 65bucks, only twenny bucks more than the SK45 basic kit - both kits fit the 545RFE\645RFE trans in your beloved CRD, as well as the 45RFE version in the lesser Jeeps.
Gotta love Ron and Mrs Joe and the guys'n'gals at Suncoast.
So, there ya have it, grasshoppers - three paths to save and improve your transmission and reclaim that great Jeep driving experience:
new torque convertor
shift kit
auxilliary fan-over cooler
Adding a trans temperature guage to your pod certainly couldn't hurt, either.
Tell 'em you heard it on L.O.S.T. KJ forums, CRD division......................
_________________
96 Dodge 3500 CTD
If it's a Diesel thing, I do understand....
#2 son's '05 KJ CRD 4wd, 53kmi;
EDGE Trail; SGII; SEGR;
Provent; Magnaflow ss;
2.5" Daystar f, OME r; Ranchos; Rubicons, 2.55 Goodyears
Suncoast T\C, Transgo
'06 Cummins lift pump module, filter manager
Trail (and now Stream) rated
Four in a row makes it go
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So no US CRD's came with the new pump and cover 
Only those CRD's that had a noise the technition could hear got the new pump and front cover with F37 
According to something I recently read hear the original torque converters that were in all 05's and 06 models before 11/05 had a "cushion" thing who's rivits would loosen and fall out. They were replaced by the older style without the cushion.
