I have a 1996 Dodge Ram 2500 conversion van that won't shift into drive. I can manually shift through 1,2, then up to drive but not straight into drive. I replaced the transmission oil from the pan only. Could it be the Torque Converter? Or do I need a whole new transmission? I am a broke college kid living in my van, and I would greatly appreciate the advice. Thank You.

 

I have heard of this problem before. I believe you will be able to find the answer here if you search for it.
Regards, Steve

 

This should help.