Well, having owned both the GM 6.2 and the Ford/IH 6.9 engines in various vehicles as well as more than a couple of gassers, I guess I can give a
somewhat unbiased opinion of the vehicles you are thinking about.
First of all I will start with my 1989 GMC K1500 4x4 regular cab/long bed with the 5.7 gas engine and TH700R4 transmission. I've owned it since about 60K miles and it's now just passing the 300K mark and I will say that it is an extremely reliable, capable, customizable, durable, truck that I get pretty decent mileage with. With the 3.42 axles, Dual Optima batteries, K&N air filter, Mobil synthetic 5w40 oil in engine, synthetic transmission fluid, all other fluids are synthetics, 265/75-16 AP tires, a few other mods (all legal and passes emissions) and I get 20 HWY cruising at 70 or more with a big fiberglass cap on back. With the 2" receiver hitch in back I can pull whatever I need or want to (though not in OD). I replaced the engine with a Goodwrench maybe 100K after I bough the truck used, and the transmission RIGHT after I bought it because I wasn't aware the previous owner used to just pound the truck hauling extremely oversize loads to a GoodWrench replacement that is still running without hiccups. And I've used the truck on the farm pulling loads, moved out to WY and back to WI with a few trip back and forth in between cruising at 80+ mph in OD with cruise and air conditioning running as necessary. It hauls extremely steady with power, and I have gone through some INCREDIBLE amounts of snow with no locker only an open rear end and have also pulled a few friends and my Dad out of snowy and muddy ditches as needed. The worst mileage I ever got was
13 mpg when the truck was new and needed a tuneup badly and had a bad tranny, to a best of
24 mpg doing 80 in Nebraska in OD always running synthetic lubricants and at minimum 91 Octane fuel. I still own the truck, it always starts no matter the temp, and am still on the original fuel pump even though I need to change it.
Now there's the 1986 F250 2wd super cab long bed truck with 6.9l diesel and C6 auto tranny that I bought from my parents who used it as a farm truck. There was a gooseneck hitch put in back and a 32' flatbed trailer with beaver tail that was frequently used to hail everything from HUGE loads of hay, tractors and other farm equipment through rough fields and on the road, and with wood sides made for it more than a few people were moved around as well. I know when my folks owned it it was abused with long durations of time between oil changes in the engine and transmission (in fact I don't think they ever changed the tranny fluid the way it looked when I would occasionally change it for them once a year or so with regular oils). So when I bought it, there wasn't a straight panel on the truck having had been hit by tractors, trucks, the skid steer, run into by large Holsteins, and no transmission kickdown hooked up to it. I quickly found out that only a few glow plugs worked and it started hard until it got cold out when it needed to be plugged in to start and with no glow plugs energized I put an ether assist button on the dash for cold starts. I changed all of the filters, lift pump, hooked up the vacuum and kickdown on the transmission and changed all the fluids to synthetic. I was fortunate that the seals were still really tight and there are no leaks and good oil pressure. Now this engine will run around
20 mpg whether loaded or not, and I've had it so loaded down that the overload springs were being utilized by the truck and the front was up with the back down. It looked comical. But it will also burn every diesel I toss into it, and plenty of other oils and fluids as well. But with a couple of additives with every tank, I get that good mileage but I tend to drive
50-55 mph tops when on the highway. It feels like a vehicle that wants to just cruise and enjoy the ride anyway.
With a 1982 Chevy Suburban 1/2 ton 4x4 that has a 6.2l diesel and 700R4 in it, and a 1984 CUCV M1009 (the military version of the Chevy Blazer 4x4 that's equivalent to a heavy 3/4 ton with less amenities and EGR on it) with the 6.2l diesel and th400 tranny in it I get similar mileages and that's with much different setups. The Suburban is pretty much stock with 31/10.50-15 tires on it and 4 speed overdrive, and the Blazer has 37/12.50-16.5 tires on it with a 3 speed and no overdrive. They both have good glow plugs in them and start easily and dependably. There are hitches on them both, but I rarely haul any trailers with them since I have so much room inside and I like hauling with the GMC truck because I have stiff suspension on it and it has more comfortable seats I put in afterwards while the Suburban and Blazer have stock seats in them. They both hold at least 5 larger people comfortably, though the Blazer takes a little more of a hop to get into it because of the height. As usual I put synthetics in them both wherever I could, and they are a little rougher on the steering system and need to have joints changed a little more often, especially on the CUCV. The Suburban in stock form had gotten about
30 mpg on long trips with just a load of a few passengers in it and new tires. The Blazer, with the large tires that fit without a lift due to custom rums with the right offset that allows for off-roading without hitting any of the body panels, was giving me a consistent
~25 mpg on the highway and
~20 mpg mixed stop and go traffic with a full tank of diesel and a couple of additives put into it. With the lower cetane ratings and quality of the fuels today, I will often put in some 2 cycle oil into the fuel tanks for the benefit of the injection pump, which does seem quieter with the additives in. Now both GM vehicles have factory traction aids in the rear ends with the Suburban having a
"posi-traction" unit and the Blazer having a
"Gov-Lock" in it's similar 6 Lug 10 Bolt rear end, and both have HydroBoost brakes which operate off of the power steering pump and not engine vacuum like other vehicles and have incredible stopping power. The worst mileage I got with the Blazer was a heavy snow storm last year where I drove a couple of hours to the cabin in 4wd getting
15 mpg hwy doing 35-40 in heavy slushy snow. And though some people don't like the
"Gov-Lock", I've found it to be an incredible aid in maneuvering the short wheel base Blazer in sloppy conditions.
Of course the diesels are all a bit louder running than any gas powered vehicle, and tire choices DO add to the noise especially with the HUMMER tires on the Blazer. But any vehicle can hold the weight and have the ride you want depending on the choice of suspension, shocks, tires and other sway and roll controls as well as seat choice and vehicle comforts such as insulation and carpeting or bed liners added on.
There are definite factors like a longer wheelbase vehicle tends to haul a trailer with a little more resistance to lateral swaying due to weight being hauled behind, and a shorter wheelbase vehicle is easier to maneuver around in tight areas or park in a smaller area. Diesels require a little more care in colder weather in order to start or keep going as fuel will gel up and not flow well enough to run the engine if it is TOO cold and there is no treating the fuel ahead of time. Diesels can run on a wider variety of petroleum products including waste oils and even vegetable oils. Diesels tend to haul heavier loads more efficiently, but are heavier vehicles as well.
Gasoline powered vehicles can start in cold weather a lot easier, but sometimes require a certain octane fuel or they will lose power and efficiency as timing changes. They can run a lot quieter, depending on the exhaust system you choose, but like any vehicle need to breath freely. Gas vehicles are usually less maintenance intensive and for the most part cheaper to maintain.
You know, I can keep rambling on all I want, but for the most part the right choice for your needs are dependent on what you like. Like anything, the best thing to do is to ask owners of different vehicles of what they like about their rides, and see if you can test drive as much as you can and formulate your own opinion. And remember, tire choices will affect noise and performance so that is
ONE more detail to consider...
So did I help or confuse you?
