Mine is out of a Chevy Kodiak 4500 with 4.78 ratio... It will require me to find a new 3rd member at some point so I can match my D60 front. My plan is to drive it for a while and then either go up to 4.88 or in the more likely case, down to 4.10 with the factory Posi traction unit.That Dana S135 was the strongest rear ever in a non medium duty truck. The Ford F550 used it for several years but they eventually changed to the S110. The S135 was just overkill in those trucks. What gear ratio does yours have?