I have a leak between the tranny and the pass side axle. Although, I do not have a diagram, some have told me that there is a seal in there .. I am trying to find out if it is replaceable with the tranny mounted in the car.

Thanks in advance for your help.

 

There is a seal there. If the problem is where you say it is, that is actually the differential. To service that seal, the drive axle must be removed.
Several special tools are needed to do that job. Even if you are not planning to do it yourself, you might want to buy a Haynes or Chilton manual or a Chrysler shop manual so you can discuss the job intelligently with your mechanic and understand what it is that he will need to do.