Difference - LWB and SWB fuel tanks?

[kevinr1970]

Are they the same or different? If different, could I use SWB tanks in place of LWB tanks?

Reason for asking is I have an '86 GMC 4x4. I replaced the engine with a rebuilt engine with a hot cam and although I have finally gotten it to run right, the mileage is extremely poor and judging by the smell of the exhaust at idle its never going to pass smog test.
I have a 2wd Blazer project with no emission concerns that could use this engine. I have an '87 parts truck with TBI 305 that I would love to put in the GMC as I drive it fairly often and could use the better mileage.

[74Chevy74]

They are different, LB came with a 25 gallon tank, and SB came with a 16, in rare cases some LB's had 16's. I have a LB that I shortened to make a SB and I had to put a 16 gal tank in it, the tank has two straps that hold it in each with 4 bolts, the front lines up but the back only 2 bolts line up, so you have to redrill 2 holes, it's real easy if you can take the strap of the tank and use that as your reference as your under the truck, much easier than holding a huge tank up. Hope this helps!

[bigblock73]

Long boxes usually came with 20 gallon tanks...short beds all had 16 gallon tanks.

[74Chevy74]

Originally Posted by bigblock73

Long boxes usually came with 20 gallon tanks...short beds all had 16 gallon tanks.

OOOPs! yeah that's what I meant! Sorry about that. I was thinking 25 cause that what some blazer/suburban's are.

[kevinr1970]

My GMC must be one of the rare ones? It only takes about $25-$30 to fill one tank. Don't really pay attention to the gallons, but gas is about $2.29 right now.
So, if my truck has 16 gal tanks now the tanks from the SWB should bolt right up? I tried to look at a few parts suppliers and they didn't have any notes for SB vs. LB so it looks like they are the same.

[piecesparts]

If you want Short tanks in your LWB truck, they will bolt in just like a SWB truck. They just won't fill up the space like the long tanks would.

[72 CustomCamper]

Originally Posted by bigblock73

Long boxes usually came with 20 gallon tanks...short beds all had 16 gallon tanks.

Unless the long bed came with dual tanks then it got a pair of 16 gallons...


Chuck

[Russell]

The 16 gallon tanks are both nice, and not, lol

It only costs 45 bucks to fill, once a week, but a guy can only go like 300 - 320 miles on a tank (highway driving), even less city driving... Feels like you've gotta stop at every gas station, and its a bit stressful if your gauge gauge wire came undone (with a stepper, there is no way to reach under and put the wire back onto the sending unit without pulling the bed)

[swb85]

I think if they were going to use 16 gallon tanks they should have at least put two in the swb. I only have one 16 gal and I have yet to get more than 175 miles to a tank. I have a real hard time driving by gas stations.

[86 GMG]

my 86 swb has 16's and my 84lwb has 16's also but a 77 lwb partsd truck i had had 20's but it appeared that the p.o. installed the second tank my god the are huge to wrestle out by yourself and half full this is just my experiences and not known to be accurate to what they installed factory but we all know how gm thru things together sometimes with what they had laying around

[Russell]

Originally Posted by swb85

I think if they were going to use 16 gallon tanks they should have at least put two in the swb. I only have one 16 gal and I have yet to get more than 175 miles to a tank. I have a real hard time driving by gas stations.

Overdrive and a light foot help that problem, lol

[79BIG10]

Originally Posted by swb85

I have a real hard time driving by gas stations.

I know the feeling. Try having two 20 gal. tanks both have to be filled with 92 octane or better (nothing less will work in engine) and no OD tranny with 3.73. Wors great in town but when you hit the loud pedal the speedo moves as fast as the fuel gauge.

[swb85]

Originally Posted by 79BIG10

I know the feeling. Try having two 20 gal. tanks both have to be filled with 92 octane or better (nothing less will work in engine) and no OD tranny with 3.73. Wors great in town but when you hit the loud pedal the speedo moves as fast as the fuel gauge.

I feel the pain man, I've got no overdrive and 3.42's. Get a whopping 12mpg if I keep my foot out of it and shift under 2k rpms. At least you have 40gals to get you more than 3 days between fillups. I really need a second gas tank. Sure glad I can run on the "cheap" stuff though!!

Originally Posted by Russell

Overdrive and a light foot help that problem, lol

No kidding......one day I WILL have a t56 to replace the m22!!