Over the weekend I hauled my father-in-law's '72 GMC 4x4 shortbed from mid-MO to eastern IL. My truck is all in stock form. When I hit the hills on I-44 just west of St. Louis (around Pacific) the truck just wasn't happy pulling up those things in Overdrive. I was running about 60-65, until I got into the hills, it was pulling down and shifting itself into 3rd so I clicked OD off and ran 50-55. It pulled like a champ at that speed, but the engine was turning 2200-2300. With a stock truck and 3.55 gears should I have been able to pull better in OD? I know I wasn't running the thing out of it's specs, ate up a little extra fuel on me, though. I know I didn't hurt the truck, in fact I think I cleaned the thing out, it may be wishful thinking, but the truck just feels like it's running easier.

 

I bet you burned alot of carbon off the tip of the injectors, getting a better spray pattern now.

but that sounds about right with the 3.55 gears. the 3.73's on the 03 and up keep the engine reved a bit higher.

 

I have tended to baby my CTD for some time, and only recently started pushing it harder - only to see the fuel mileage go UP. I've seen folks on this forum say to push them, but it took me awhile to do so myself - and I can see the benefits from doing so now. So I'd have to agree that you probably helped it by doing what you did...

 

I agree, for the first like 7k miles, I kinda babied mine. Drove it like grandpa. Now I drive it like I stole it, and the cops are chasin. lol. I have noticed that it runs quieter and smoother, I haven't used the "brew" in this tank and the last one, but it runs clean and smoothe.