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

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kennythewelder

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The truck I had before the one I have now, was a 93, WT RCLB with a 4.3L, a 4L60E and it had the 34 gallon tank. My truck now is a ECSB with a 5.7L 4L60E, and it has a 26 gallon tank. IDK for sure, but GM is very good about making things universal. Oh both of my trucks were and are 2 WD. It may be worth a trip to the junk yard with a tape measure, and see what is what. If you do, I would get a tank and the brackets from there. As long as the outside of the tank looks ok, the inside should be good as long as it hasent been sitting up with water in it. You can always take out the sending unit out and look inside if you pull the tank.
 

Dravec

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As much as you don't wanna hear it, the 34 just doesn't fit in a short bed setup. Not without complications.
Your best bet if you want to increase your fuel capacity, would honestly to be to do the work to swap in the rear mount tank from a Tahoe (32-ish gallons) or Suburban (42-ish gallons)
 

RichardSwinger

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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.
3.73 per the RPO codes in the glove box and the printout I got from the parts dept of my local GMC dealership. I went there because I was afraid of messing with the steering wheel (trying to chase down why the horn isn't working) after my dad told me about the airbags being 22+ years old and possibly exploding in my face. Come to find out, this thing has zero airbags, which is a double edged sword. Airbags do enhance safety but 22 year old airbag components would be suspect for sure. Luckily that means that a steering wheel swap should be much easier and zero liabilities since there isn't any safety stuff that would be disabled. The cherry on top of that dealership visit was learning they can get me two OEM key fobs for the electronic locks for about $100, where as the cheapest aftermarket fob purchase/install local to me was about $175.

I'm still learning the lingo, what does 14 BFF mean? I didn't know what the heck hydro boost was until my cousin pointed it out to me after seeing pictures of the engine bay.

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stutaeng

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As much as you don't wanna hear it, the 34 just doesn't fit in a short bed setup. Not without complications.
Your best bet if you want to increase your fuel capacity, would honestly to be to do the work to swap in the rear mount tank from a Tahoe (32-ish gallons) or Suburban (42-ish gallons)

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.

I think the GMT 800 suburbans got a dual tank setup, but I think it's only like 38 gallons? Mine has that setup, but don't know how it works, and I rarely have enough cash to fill that thing up anyways, LOL.
 

RichardSwinger

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As much as you don't wanna hear it, the 34 just doesn't fit in a short bed setup. Not without complications.
Your best bet if you want to increase your fuel capacity, would honestly to be to do the work to swap in the rear mount tank from a Tahoe (32-ish gallons) or Suburban (42-ish gallons)
Oh if it doesn't work I definitely DO want to hear that to prevent me from going down a bad path. You mentioned complications, what kind? Did you or someone you know try this before and have it go poorly? You mentioned some different tanks other than the 34, are those an easier tank to swap to? Thank you for your help!

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Supercharged111

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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.

I think the GMT 800 suburbans got a dual tank setup, but I think it's only like 38 gallons? Mine has that setup, but don't know how it works, and I rarely have enough cash to fill that thing up anyways, LOL.

Tahoe tank fits a short bed, Suburban tank fits a long bed from what I've read. The chassis cab stuff is different because the frames were different.


Oh if it doesn't work I definitely DO want to hear that to prevent me from going down a bad path. You mentioned complications, what kind? Did you or someone you know try this before and have it go poorly? You mentioned some different tanks other than the 34, are those an easier tank to swap to? Thank you for your help!

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I'm 99% sure the big tank doesn't just bolt in. I have both and believe I measured at one point. It's going to hit the axle IIRC. If you were feeling froggy you could shorten a 34 gallon for a little more juice. What I've long wanted to do is fit a small fabbed tank in front of the stocker and connect to factory tank with a hose and breather.
 

b454rat

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I thought it was this site, maybe 67-72 chevy, but I guy there built a CCSB 4wd. Did a small lift, 454.4l80, and tried a 35g and didn't fit. He ended up making a whole new tank, and gained couple gallons. I'll see if I can find it. Best bet for a bigger tank is a Blazer or Burb tank...
 
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