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We recently had to upgrade our work truck for more hauling capacity. We haul about 12,000lbs 500 miles, (with 500 miles empty first on same trip.)

First some data about the nut behind the wheel(the biggest factor), and then I'll ask you to guess what my new mpg will be.

Past efficiency projects:
5+ metros, routinely 60+ mpg, old blue would break 70 for me, best ever 72mpg

94 ranger, 4cyl 5 speed, averaged 36mpg through time I owned it, installed a kill switch and broke 40mpg, totalled by a drunk driver soon after.

92 Cummins 12v 5 speed 35" tires (I promisei needed them, I did home health care in a very remote area, could not say wait, when the mud, snow or creeks git deep) real consistent 24-25 empty to 2000lbs load

93 Ford e-350. 7.3 idi pre power stroke diesel, overdrive automatic, converted to 6 speed manual. Mostly long trips, warm weather, averaged 24mpg tanks pretty consistently with the auto, usually <1000lbs load. hadn't even finished my first tank post zf6 swap and was offered enough money for the van to put a down payment on a house.

Chevy suburban 5.7 overdrive automatic. 17.4mpg total miles averaged empty, 13.7mpg average loaded to max load of 10,000lbs of green lumber.

Finally, the new truck. You can see from my old projects I almost always buy busted stuff and fix it to save money. This is no exception. Picked up an 2007 Chevy Silverado 3500, duramax diesel, with the 6 speed Allison automatic for a song, cause it had a popped head gasket. Don't recommend this project for the faint of heart, book hour estimate is 40hrs, and that's in a shop with lift and air tools etc. But my cheapness knows no bounds.

I had always wanted to mess around with the newer computer controlled diesels, but had held off cause of cost. Been pleasantly surprised so far with this one. Because the computer can compensate, you can rebuild your own injectors, so in a way it is more user serviceable than some of the old mechanical diesels, the yardstick of extreme reliability in a machine.

So I'm sitting here waiting for some parts in the mail to finish the head gasket job, and I'm wondering, eccomodder community, given the data on my hypermiling past, what do you expect my milage to be with the new truck? Stock tire size, if Vin number isnt fibbing 4.10 gears, Allison has a sweet 0.61 overdrive ratio. Truck will be driven on the same loop, 500 out empty, 500 back loaded to the gills with a trailer, occasionally across town with <1000lbs in bed. So what will my empty highway mpg be? 12000lb trailer highway be? Empty town be? And lightly loaded 500-1000lbs around town be? I promise to deliver some hard numbers as soon as I have them, we can see who got closest ;-)

Doing head gaskets on a dramax is why I probably won't ever own a duramax.

Haha, yeah, it's no picnic. But when the dust settled on the horse trading I got it for $1200, totally because of the head gasket reputation. Only tricky parts so far is needing to use 1/4" drive sockets for clearance on intake bridge bolts, and I re pissed off my my herniated disc getting exhaust manifold to up pipe bolts out. Thought I was smart doing those 3 hard to reach boots instead of the ten easy to reach exhaust manifold bolts. One of the 3 you can only get a box end in, I'm a pretty big guy, and was able to get it going with a 6" wrench, at the cost of my spine health. I came to my senses and bought an impact wrench to zip out the 10 easy to reach bolts on the other side. Learn from my mistakes friends. So far I'm in it $1140 for parts, for mahle gaskets ARP head studs(never want to re do this) and a couple valves, new cylinder head, couple pushrods. So $2340 and my time for an 07 duramax 3500, studded, brand new head etc.

Oh it was throwing a bunch of transmission codes when I bought it, dropped the pan and it had a dent that was touching one of the solenoids, pounded it out on the old anvil, and no more trans codes.

Progress...progresses? New cylinder head came in, measured the bee-jesus out of it, and it was pretty darn flat. Lapped old valves into new seats, just barely. Not to remove material so much as to confirm a good mate-up.

But in the course of this, I discovered two more dud valves, dang! so now I'll have more parts waiting. If only the brick and mortar places weren't 3x as much $$ as rock auto etc.

Finishing up the coffee, and then will head out to install valve springs on all the good valves. Will try to figure out how to put pics on here. This is my first fancy electronic diesel, so may end in tears and self loathing if I can't get all the electrical and plumbing "tentacles" hooked back up correctly, Hah! Wish me luck.

Sounds like quite the project! Good luck. :)