Beginning at the start of production for the 1999 model year Chrysler Corporation has introduced a brand new rear wheel drive transmission for the 99 Jeep Grand Cherokee with the 4.7L engine, and scheduled for the Ram Pick-up for the 2000 model year. This is the first completely new rear wheel drive automatic transmission from Chrysler in more than thirty years. The 45RFE designation tells us that this new unit has 4 forward speeds, a relative torque rating of 5, is for Rear drive vehicles and is Fully Electronic controlled. The 545RFE was introduced in 2003 in 3.7 and 5.7 engines. There are few differences in the components between the 45RFE and the 545RFE, although the main difference is the addition of a fifth ratio, which is electronically controlled.

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