Originally Posted by snrusnak
There seems to be some confusion on the different transmissions:
68rfe diesel6 speed transmission in HD trucks
66rfe gas 6 speed transmission in HD trucks(essentially 68rfe internals in a 545/65rfe case)
545/65rfe gas "6" speed transmission in 1500 trucks. Uses 5 gears in typical upshifting
45rfe gas "5" speed transmission(same as 545/65rfe but different programming). Uses 4 gears in typical upshifting
I'd LOVE to have the 66rfe in my truck(even more so than the new 8 speed...). MGH if you ever figure it out please let us/me know. How exactly are you trying to go about it?
Mike is building up 545RFE's using superior 68RFE frictions, machining room for substantially more of them, boosting pump pressure by 40-50 psi by modifying the pump and reworking the valve body, and its for greater holding power under boosted applications. Then tuning it all to work in harmony, in many cases with an ATS Triple Disc 3000 stall TC.
IOW, No real a benefit for an NA 4.7L Ram
It's still the same 545RFE gear ratios, just more holding power under boost. If you attempted to swap actual gears/planataries from a 68RFE to a 545RFE there is still no way to program it to adjust for the different ratios so your PCM wouldn't throw incorrect ratio codes. (and the 66RFE ratios are the same as the 545RFE)