I have just recently bought a 2007 Dodge Ram 3500 mega cab with a 6.7 l Cummings Diesel I do not know if anything has been done to the transmission and the sense of filter change or fluid flush it has 134,000 miles on it should I change the filter and fluid or should I have a flush then change the filter?

 

Just change the fluid and filters. Yes there are two filters, a spin on and pancake filter in the pan. Buy Mopar or Fleetguard filters and don't stress on buying expensive fluid. Any fluid that meets the specs in the owners manual are good. I used Walmart generic brand fluid and it was on the Ram approved list.
Plan on 9-12 qts for the fluid change (depending on how long you let it drain).

Read up on the fluid/filter change a bit as there's some cautions to be followed like don't overtightened the screw on filter because the nipple is made of plastic and don't replace the pancake filter seal unless the old one is in bad shape and if you do you need to, seat the seal flush with the body.

 

Alright thanks for your help appreciate it