Question for all you 1-Ton owners...

[DieselSJ]

Originally Posted by Alex V.

My truck is an '85 C3500 with a bone stock 454, tired TH400, and 4.10 gears with the correct 235/85/16 tires. When pulling a decent load (i.e. car on a trailer) hitting a hill at less than 50 MPH takes a lot more pedal to keep speed over the hill than if I'm going at least 55 when I start up the grade. The transmission has a strange drag/mild vibration that it hasn't always had, but that being the case it feels best at about 60 but doesn't mind upwards of 65. It'll do 75+ if asked, but sustaining over about 65 puts a dent in gas mileage and I just don't care to push the truck that hard for long distances.

I had a weird vibration/surge at mid-rpm. Turns out my balancer was slipping and coming apart. I posted a pic on here a while ago. New balancer and vibration went away.