I have a 2005 Dakota 4X4 quad cab with the 545rfe trans. My truck went into limp mode and when I plugged in the OB2scanner it gave me codes for a third and forth gear solenoids. I changed out the Solenoid pack and now it is giving me a P0750 and P0700 codes. Does any one have any suggestions on what may be the issue and how I can get it fixed.

 

Unfortunately neither of the two codes gives a clue what the problem could be. Both codes are just information codes, just letting the Powertrain Control Module 9PCM) that is the a problem with the transmission. I recommend starting with basic inspection, transmission fluid level and condition, and also make sure the battery is fully charge and terminals are clean and secured.
After the inspection, try clearing the code and test again. If the problem persist, then you may have to have a transmission specialist inspect your vehicle

 

From the manual. Hope this helps