For what its worth although my truck is a one ton weighing in at around 6,000 lbs. I found 2000 rpm to low at highway speeds . I found at that rpm. every grade or cross wind would have me searching for a lower gear . I eventually switched the rear end gearing to run around 65 mph . at 2,500 rpm .
Both seat of the pants observations and the vacuum gage back up this move .
John
