6.9s were made from 83 thru 88 or 89. Then they were up dated to the 7.3. Both motors were Navistar engines. Buy your parts from the Navistar or IH truck dealer. Good engines, but not much power compared to what is available now days. Both of the ones I had would get close to 20 MPG in 1 ton 4X4, but they were both "Nickized"