I have had to do a lot of driving lately and it seems like it may continue for a while. I hate to do it but there is no reason to drive something this big back and forth from NC to VA every week or two. Besides the fuel is killing me. I need a little four banger car. It's not up for sale yet but I am thinking about it. I may wait and see how much fuel the turbo saves me, and how much more I like to drive it with the turbo before I decide. I always wanted a dually crew cab and now that I have one I may have to sell it. Darn it!!

What do you get for mileage?
How fast do you drive it on highway?
How is it geared?

I've got a '94 3/4-ton 6.5 with 3.73 rear end. With the overdrive tranny (4L80) it runs 1950 rpm at 58 mph, and will do approx. 22 mpg.

That's very close to a Subary Outback station wagon with 4-banger engine.

The truck used to have electronic injection but I've changed it to 6.2L-style mech. injection, with no change in mileage.

You should be able to get good mileage unless you're geared 4.10 or lower.

If you like the truck, you might consider re-gearing instead of selling it.
Re-gearing in a professional shop might cost around $500-$700 per axle. That's cheap compared to sacrificing the truck you like.

The key is to calculate your gearing to have the engine running at 1700-1900 rpm at your ideal cruising speed.
Also, don't forget that there's a huge increase in fuel consumption for driving fast, and that's aerodynamics, no matter what gearing you have.

Good luck

Another point: don't waste your money on the turbo. (Unless you want more power)

My truck had one (worked well for boosting power). I was curious to know how much fuel it saved on highway trips, so I took it out and re-did mileage tests.
NO DIFFERENCE!
Turbos may be good for increasing power and improving mileage when towing or otherwise loading the engine, but for normal highway cruising they are useless.

BTW, are you sure that your injection timing is adjusted right?
Incorrect timing might really affect mileage.

To check injection timing I've used this trick:
Hook up a cable and switch that allows you to manually switch on/off the Cold Advance Solenoid from the driver's seat.
When switched on, it advances timing by 3-5 degrees.

Warm up the truck and drive it on the highway.
Maintain a steady throttle level.
Then switch on the Cold Advance.
If your truck accelerates, that means the additional advance has brought the timing closer to its ideal (most efficient) setting, so your timing is set too retarded.
If it doesn't accelerate, you have enough advance already.
If it decelerates, your timing is too advanced. (No good!)

When engines are rebuilt, or have their timing cover replaced, the timing line mark may become invalid, so just setting the timing line-to-line may cause retarded or even (worse) over-advanced timing.

Hope this helps

Being an '82, unless its had tranny upgrade done, it doesn't have an OD tranny. That'd be the first thing I'd do, especially for the over the road highway miles you are driving.

Reading this really makes me want to keep the truck. It is geared low, very low. Probably 4.10, but I am not sure. I have thought about changing the trans so I have overdrive. I bet both of those items would really help, but I don't know if I want to do all that work. I was injured a couple years ago and I am really not supposed to be doing that kind of stuff anymore. I think it's time for me to realize I am not a young healthy man anymore. I am going to check my injection timing ASAP, I can do that much. Thats a pretty cool trick.

What makes me want to sell is that I can find a car that gets 35mpg easily. That would be a HUGE money saver for me. I have it listed for sale here and on Craigslist for $3500. If I can get my asking price, I am going to let it go. If I had money to keep it and buy another car I would do that.

:bawl: Thats sad to have put that much effort and TLC in a cool old truck, then have to sell it because of the fCensored gas prices!:bendover: