25 gallon to 34 gallon gas tank swap, can it be done?

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df2x4

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I was wondering how the suburbans got that ginormous tank in there vs the trucks? Is it a single tank? Especially because the wheel base is maybe shorter, compared to like an ECLB.

From what I've seen it's because the 'burbs relocate the spare tire inside the vehicle and mount the tank (approx. 42 gallon) in that spot instead.

Tahoe tank fits a short bed, Suburban tank fits a long bed from what I've read.

Not sure about Tahoes but I don't think the Suburban tanks would work in a truck without some modifications, for the reason above.
 

Supercharged111

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From what I've seen it's because the 'burbs relocate the spare tire inside the vehicle and mount the tank (approx. 42 gallon) in that spot instead.



Not sure about Tahoes but I don't think the Suburban tanks would work in a truck without some modifications, for the reason above.

They both require the spare tire and it's cross members removed. Maybe it was the Blazer tank that I'm thinking of? Or was it only certain Tahoes that had the tank midship? There is a guy on this forum who put an ECSB body on a Tahoe frame and I swear he used a rear tank.
 

HotWheelsBurban

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Suburban and 2 door Tahoe/Yukon etc. the spare tire is in the cargo area, left side in the back. 4 door Tahoe/Yukon it's underneath. For the 3rd row seat room. Therefore the gas tank on them is smaller. The Burb gas tank is 44 gallons.
( yes I've filled the thirsty beastie up a few times! )
The owners manual for my 99 Burb says that the gas powered Burb was 44 gallons, diesel was 42 gallons.
For comparison, our 06 Yukon XL Denali has the spare underneath, and the gas tank on it is only 31 gallons. And gets empty way too fast with a 6.0 moving 3 tons of Burb.....
 

letitsnow

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BTW, your truck is kinda rare as far as I know. ECSB 2500 8 lug. Everything else similar got the long bed in that configuration. I think one member here has one, a white one IIRC.

14 BFF with hydroboost is pretty stout. Is yours 3.73 or 4.10?

Hopefully you can add more fuel capacity.

Mine is an ecsb 2500 8 lug, but has the 5.7.
 

94K3500PROJECT

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Yeah, you need the extended wheel base (long bed) to get that 34 gallon tank.

I know I'm the minority and everyone just loves the short beds, but this is another reason why I like the long beds. This is actually a bonus. The main reason is you can't match an 8' bed for hauling. If you are working the truck, 8' bed is great. Have you seen those dually mega crew cabs with 6.5' or whatever beds on the newer trucks? Body builder skipped leg work, LOL. Man, those beasts are grossly out is scale!

Don't get me started on the CC 1500 5.5' beds. A coworker got one and added added one of those "tough" bed covers. With a toolbox the guy has the size of of a frigging trunk! Had to get a trailer to haul a fridge, lol .

A crew cab dually short bed gmt400 looks worst of all.
And guys love them so‍♂️
 

Frank Enstein

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Ok, so... That's two people says it won't work, one guy says it's mounted in the same spot, and EVERYONE agrees that the in bed aux tank is a bad idea [emoji1787]. The more people I ask about the aux tank the more reasons against it seem to pop up, the only real pro to that aux tank would be the ease of install.

I crawled under there yesterday to do the first post build oil change and there is a surprising amount of stuff shoehorned under there. My dad knows the early flat tappet style big blocks very well and told me about this super duper FOOT LONG oil filter he used in his 427 powered dump truck and still uses in his 454 powered franken truck, but I saw that the front drive shaft is directly under the standard oil filter mount location. There is what looks like a factory installed 90° adapter for the oil filter so the filter sits horizontally vice vertically. BUT that's all on the front end of the truck and the back end seems to have a lot more room to play with underneath...

It's kind of hard to get a good picture of what kind of room there is when I'm laying flat on my back. I'm hoping to get it on a lift once I find a reputable mechanic shop local to me to help me give it a once over. I'm really hoping to find someone who has 1): tried this and been successful, or 2): tried this and knows for a fact that it won't work. Going by the pictures on Summit it does look like there is a difference in the shape of the 25 vs 34 gallon tanks at the front part of the tank, but as far as the length difference goes I think it's barely a foot longer. In studying the pictures it looks like the sherman brand 34 gallon tank is the closest in shape...
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Don't trust the images @ Summit! They often are inaccurate. The 34 gallon tank from Dorman looks just like the Summit tank.

The 34 gal tank goes farther forward under the bed.

With the body mounts being worn Frank knocked a hole in the tank because the brace under the floor clobbered it.
 
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