I think first you need to find out what engine you have. Get the serial number and it would be a good idea to get the serial number off the transmission as well. Call Cummins with your serial number,most parts counters can give you the info but you need the serial number. Ask what engine do you have is it electronic or manual. The engine that Doge uses is not exactly the same engine as you have.
Hear is where to go for your transmission.
http://www.allisontransmission.com/my-allison/customer
Bill