The only lack of power I have noticed, is when pulling heavy and fighting small rolling hills at the 55MPH speed limit. But when at 2000 RPM at 70 MPH I hardly notice them.
Again, a 68RFE equipped truck isn't going to be running 2000 RPM @ 70 MPH with 3. 73 gears. 2000 RPM with a 68RFE truck is either going to be 74 MPH (4. 10 gears) or 82 MPH (3. 73 gears). Our situation is radically different than yours. With your G56 transmission, your truck in 6th has an overall gear ratio that's lower (higher numerically) than a 68RFE truck with 4. 10s.
Rusty
Last edited: