Chrysler RFE transmission
The RFE is an automatic transmission family from Chrysler. The name refers to its Rear wheel drive design and Full Electronic control system. 45RFE and 545RFE. The 45RFE was introduced in the Jeep Grand Cherokee in 1999, it is notable for including three planetary gearsets rather than the two normally used in a 4-speed automatic. It also features three multiple disc input clutches, three multiple disc holding clutches, and a dual internal filter system (one primary filter for transmission sump, one for the fluid cooler return system). In the 45RFE applications four gears are utilized. In  the 545RFE four gears are used on the upshift and a new "gear", 2nd Prime, was used with a different (1.50:1 rather than 1.67:1) ratio to increase versatility when downshifting. Although, with some tuning, you can get the 545RFE to upshift into 2nd Prime. The 45RFE was produced at the Indiana Transmission plant in Kokomo, Indiana. It was normally paired with the 4.7 L PowerTech V8. The 45RFE later became the 5-speed 545RFE. Applications: 68RFE. The 68RFE was introduced in 2007 Ram 2500 and 3500 Pickups with the 6.7L Cummins ISB Diesel engine. The basic design and operation is  the same or similar to the 45 and 545RFE counterparts with the following exceptions: Applications: 65RFE and 66RFE. For the 2012 model year, the 545RFE was recalibrated and introduced as the 65RFE in 1500 Ram models. With the exception of an improved torque converter, it is physically the same as its predecessor. The key difference in the 65RFE is the ability to use all six forward gears in sequence when using Electronic Range Select mode. In normal drive mode, however, the 65RFE uses the shift pattern of the 545RFE; thus never using 2nd and 3rd gears in succession. 2500 and  3500 models with gas engines received the 66RFE, a hybrid of 68RFE internals (including the gearset) packaged in a 545RFE case. Gear Ratios: Applications: Basic RFE operation. The fully electronic control is accomplished by the Transmission Control Module (TCM). Depending on year and application, it can either be a stand-alone module or integrated with the Powertrain Control Module (PCM). The TCM uses data from various transmission and engine sensors to control transmission shifting. The TCM operates the solenoid pack to change hydraulic flow through the valve body to various clutches in the transmission. The solenoid pack is mounted directly  to the valve body; its connector protrudes from a hole on the left side of the transmission. On the 45 and 545RFE the hydraulic control system design (without electronic assist) provides the transmission with PARK, REVERSE, NEUTRAL, SECOND, and THIRD gears, based solely on driver shift lever selection. This design allows the vehicle to be driven (in “limp-in” mode) in the event of an electronic control system failure, or a situation that the Transmission Control Module (TCM) recognizes as potentially damaging to the transmission. On the 68RFE, fourth gear is used for limp-in instead of second and third . All RFE transmissions use Mopar ATF +4. Service fill is 6–8 quarts + transmission filter. References. http://hotrodlane.cc/New%20HEMI%20Tech/2004%2057%20hemi%20trans.pdf