72 K-20 Aux Fuel Tank

[BowTieBoy82]

I just picked up a 72 K-20 that had the factory optioned Aux Tank under the bed.... my question is does anyone make the filler neck for it... mine via the previous owner had a mild side swipe with a road sign due to a little too much to drink and the very outer end of it got distorted to where it looks like someone opened up a can of corn with a bowie knife and is beyond repair.... lmc sells the hose that runs from the neck to the tank, but not the neck itself, im almost debating on just getting an old tank from a junk yard cutting the end off the donor tank and then my filler neck and brazing it on there.... but preferably I would like to find a replacement..... any input????

[DeadheadNM]

A Blazer fuel neck might work - someone else may know for sure. You could also post a WTB here on the parts board. Good luck.

[BowTieBoy82]

LMC dont sell the filler neck for the K5's either and in their parts explosion of the fuel tanks it does appear to be the same filler neck..... I think I know what I'm going junk yard hunting for now.... but on the same token I think my other plan push come to shove to just cut the very end off a tank with the same type of mouth for the gas cap and braze onto mine would work too... wondering if anyone else has had to locate one of these filler necks or what they did if they were in a similar situation as I am in

[jocko]

Did it come out from "through" the bed with one of those silver metal fuel doors or come out in front of the rear tire?

[BowTieBoy82]

no, as a matter of fact 72 was the only year on that body style of truck they offered the aux tank, there's another fuel tank grommet with the neck protruding out of the side of the bed directly in line with the in cab tank, if you search on google 72 k-20 and look under images there's a decent pic of a baby blue k-20 with one on it, apparently not too many were made that way because untill i did some research on it prior to buying mine I have never saw one with it before

[feller]

there is a green one on here and im thinkin its a gmc, but he has one on pass side and on the drivers side. the tank is kinda half and half above bed floor and below, i think, some one else on here had one built to specs a whole new tank but that was cause the old one had a hole via rust or something. a fabbed tank like this im thinking was les than 300 i think (this is all from memory about a year ago) if you were interseted in going that route.

[black_sheep454]

In 1970-72 it was an option to get the aux fuel tank on long beds on either or both sides. My 71 gnc has one on the left that fills through the wheel opening.

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[VetteVet]

you are not seriously considering and open flame near a gas tank opening are you!!!!!!!!!!!

[BurnoutNova]

I wonder if that body glue that they use on newer cars would work for attaching the filler neck onto another tank? Avoid welding the tank that way?

[Dunenutt]

Originally Posted by VetteVet

you are not seriously considering and open flame near a gas tank opening are you!!!!!!!!!!!

Just fill it up with water before welding on it, if you do.

[BowTieBoy82]

im considering pulling the tank neck, its a neck that goes to a 6" rubber hose and then to the tank, the donor tank from a junk yard that has a similar neck is what i would cut, and I would cut it off with a cut off wheel from a air tool, and the best way to prevent a vapor explosion is a old school trick i learned from old body men that had to weld on tanks, take a hose and run it from a exhuast into the tank and purge it with carbon monoxide from the exhaust, after i cut the end off the donor tank i would only be brazing onto a filler neck with no tank backing it, seems pretty safe to me....... that tank in the fender well seems pretty poorly designed to me, good place for rust... mine is at the top side of the exterior of the bed, directly in line with the cab tank... i for one have never seen one in my life with the aux tank set up like that, maybe it was a gmc thing... if i can locate the website again ill try to find it but someone located all the old build data from chevrolet and in that generation of trucks the only factory installed auxillary tank from CHEVY (we all know gmc did some things different) was in 1972 and mounted as mine is... keep in mind just seeing one dont mean it came that way... these trucks are all 39+ years old..thats allot of time for people to say "i think this would be a good idea" while drinking beer... and once again, there is no open flame issue with the brazing, from the bottom up it is a fuel cell, a rubber hose, and a metal filler neck going through the bed.... the only thing i will be brazing on is a metal filler neck thats seperated from the truck itself.....

[BowTieBoy82]

and im trying to keep the truck all original in regards to the exterior thats why installing a different tank and rerunning things is not an option.... hell i may not even use that fuel tank, I just want to be able to put a cap on it and not have a rag stuffed in it with duct tape over it..... if it was immaterial to me and I didnt want to keep the truck original i would just shave and cover the hole in the side of the bed where the neck comes out... but seeing as how you dont see a whole hell of allot of k-20's out there (and i know this is a forum so there's probably a bunch on here but c'mon guys, its not like you see 1 going down the road every time you go grocery shopping) i want to the keep the truck intact and as original as i can....

[VetteVet]

im considering pulling the tank neck, its a neck that goes to a 6" rubber hose and then to the tank, the donor tank from a junk yard that has a similar neck is what i would cut, and I would cut it off with a cut off wheel from a air tool,

I thought you might be doing this after I had posted but I was being cautious for your sake.

[BowTieBoy82]

oh yeah, i appreciate it, ive got a lil more then just common sense in the garage area lol..... yeah, the only tank there would be a possible explosion issue is with the donor tank ill use the very end of its filler neck off which i would probably just fill with water since it will be junk anyways after i get done.... id still like to know if anyone knows of anywhere you can get a filler neck for one of these vs me having to pay for a junk fuel tank to do what i talked about to

[special-K]

Since no one offers any replacement parts for the '72 aux.tank set-up you'll need to find a the used parts or something like you are planning,which sounds like a plan.

I have always said these were '72-only,but in a '71 Custom Camper brochure this option is one of the suggested available options. I've never seen a '71 with this set-up and maybe,although it said it was for '71s,it was actually just printed then knowing the tank would be available by the time the brochure was out which was when the '72s would be too?
But, '69 also had an aux. tank option,although they are rarer than hen's teeth. Those tanks were rear mounted. All the saddle tanks that either filled through the Paxton doors,wheel well,or just straight out the side were aftermarket and very very common...but not factory.

[One Chevy Scotty]

My 72 K20 has both tanks (one on either side) their necks are through the bed side and at the same level as the behind-the-seat tank, and they use the same grommet. They are mounted on top of the wood floor and bolt to the bed rail, floor, and bed front (high). They have the same caps as the main tank as well. The valve is located next to the seat (through the floor board/rocker). I had some pics of the tanks in one of my threads around here somewhere....

I had the aux tanks rolled in abrasive (inside) and coated....the shop said that they are even baffled on the inside and had to cut 2 additional holes in the top of the tank to get good coverage of the sealer (and to get the leftovers out). The tanks are pretty large, I'm guessing 20-26 gallons each...I have not put fuel in them yet (another to-do on the ever growing list)

Found the thread that has the photos...Post #18 has the fuel tank shots http://67-72chevytrucks.com/vboard/s...d.php?t=453984

[special-K]

Those are probably Desert Dynamics tanks or maybe Hickey Enterprises. I imagine other companies made them,too. My '72 parts Blazer has that type by Desert Dynamics but mounted behind the wheel houses.


I read your thread and the truck looks awesome! I read you thought those were original 16" wheels and thought I'd let you know,in case you haven't learned different since then,those actually are not original to these trucks. The 0nly 16" wheel offered with these trucks was a split rim. Later on GM started offering 16" clinchers and it's a nice upgrade.

Here's the '69 factory auxiliary tank:

[DeadheadNM]

Originally Posted by special-K

Here's the '69 factory auxiliary tank:

Wasn't that tank an option in 1970 as seen on this post?: http://67-72chevytrucks.com/vboard/s...d.php?t=468296

[special-K]

Maybe it was '70. I saved those pictures a long time ago and they say 69 auxiliary tank in the code. It may have been both years,too. One of those things that you see so rarely it could be hard to nail down unless you have dealer lit.

[DeadheadNM]

As an FYI about this rare aux tank option. This is what KrazyRay told me about the factory mod required to get the necessary clearance for that rear tank:

"The tall bed support that gets in the way of the rear tank was not on that bed. The factory instead installed a short bed support...the same support that is in front of the wheel tubs. They used shims to make up the height difference to the frame. That's probably why it worked with no extra mods."

I've got the parts to install both this and/or the 72 aux tank in my 72 K20. Not sure if I will do either yet as I hate to cut what is a really choice bed (came off a truck with a camper) and would have to modify a dealer travel tank to work in place of an actual 72 aux tank.

[wyo tim]

I've got a 72 with the holes on both sides where someone decided to remove the tanks. I would love to find the filler pipes also. I'm thinking of cutting a piece off a junk yard tank and having a local exhaust shop bend a new on efor me.

[BowTieBoy82]

I think my fix may not be that difficult as I percieved, like I said in my case the tank, the hose, the filler neck are all there, its literally the very last 1/4" of the neck that protrudes thats damaged, i work on oil drilling rigs and wont be home for another 10 days or so, when I get home I can post a picture of what the issue is I have to deal with, but pretty much where that guy hit a road sign it mashed in the inner part of the end of the filler neck to where you can not get a fuel cap on it... the outside of the neck is fine, the inside looks literally like imagine it was once capped off and someone used a old school can opener to open it... and its so mangled where there are shards of metal where the tabs were for the fuel cap to lock in it's not workable to try to fix it... so in my case i think just finding another fuel tank that took an old school gas cap of the same outside diameter weather its off a motor vehicle or a tractor and cutting the ends off the donor and my neck and brazing it back on..... but wyo thats probably a good solution you have if your missing it period, just some exhaust pipe and a donor tank for the fuel cap end

[pritch]

Originally Posted by VetteVet

you are not seriously considering and open flame near a gas tank opening are you!!!!!!!!!!!

You shoulda seen how well that worked out for us in shop class one time

I was junkyarding just today and I saw a '72 with the little doors, on each side of the bed. 3 tanks on that one. You know what, it was a '71 'cause I was going to get the rear view mirror but the screws wouldn't budge. Never mind.

[BowTieBoy82]

what are those filler necks made out of I havnt pulled mine yet but if its aluminum I may have found the answer to my problem without having to buy a donor tank to lop its end off... search on ebay: Coyote-Gear Aluminum Gas Tank Weld On Filler Neck With Chromed Vented Cap

[special-K]

I think they are galvanized steel.