Well I have heard a different story. The 545RFE is a six speed box, having two second gears, one which is used going up and the other going down. It is a five speed box assuming your counting the overdrive gear. I believe it is the same box as the 645RFE which of course has six speeds and this is possible due to the planetary gear arrangment. Green Diesel Engineering does produce 545RFE custom TCM flashes and sells these in Australia through CRDSTU (who is their local agent). I should point out that this is only for the CRD. I know this because I have a GDE TCM which has significantly different shift charactertics to the stock TCM: for example, it will upshift at lower rpm to allow the engine to lug when under light load situations and it gets better fuel economy than the stock shift points. The shift points are altered to avoid that 'hunting' that happens around 80kmph (which is a fairly common speed in built up areas here). Towing is somewhat problematic with the GDE 'stock' TCM tune as the last thing you need is to fall into a torque hole with an early upshift, so GDE has also created a Towing tune which allows the holding of 4th gear to a much higher RPM than their 'stock' tune. I should add that GDE also uses torque converter lockup on 3rd, 4th and 5th gear, which reduces transmission temperature (your off the pump so to speak) and improves fuel economy. You can manually control gear selection through working the system to stay within it's rpm band better than the stock TCM and so effectively locking it in 3rd, or 4th can be done and the Overdrive button plays a role in controlling that. I admit I still have not mastered the art of manually controlling the gear used so I just mainly rely on the GDE programmed shift points. I believe GDE also offers TCM customisation, where they will set it up to suit your needs or special requirements. For full details talk to Stu, or read about it on the GDE website. I don't think there are many running in KJs in Australia, and again, GDE TCM tunes are really only for the CRD, which has the necessary torque curve to allow lugging and benefits from the lockup profile.
BTW the Dodge RAM TCM does get used by the US Liberty guys, but again its pretty much the CRD guys trying that out.
Finally, here are the gear ratios for the 545RFE and the 645RFE:
Look at these gear ratios, notice how they used the two 2nd gears to introduce a new 3rd, so that 6th is actually the same as 5th in the 545RFE - think of it as a closer ratio box):
545rfe
1st 3.00:1
2nd 1.67:1
2nd Prime 1.50:1
3rd 1.00:1
4th 0.75:1
5th 0.67:1
Reverse 3.00:1
65RFE
1st 3.00:1
2nd 1.67:1
3rd 1.50:1
4th 1.00:1
5th 0.75:1
6th 0.67:1
Reverse 3.00:1
More info here:
http://www.ramforum.com/f44/545rfe-29487/
WANTED ... KJ 2.8CRD auto trans
"NOT speeding OFFICER , im Qualifying "
