55.2-59 Under bed fuel tank help

[Missyblue]

Hi this is just the start of an idea but I'm hoping for advice.
To mount fuel tank I know most people move the crossmember between the shackle mounts to the back. But could I cut and leave the top portion like in number 1.

My shock crossmember is broken. Would you repair or remove? I have a 70s axle and it actually has shock mounts on the cab side so maybe fab a mount and crossmember on the cab side?

The other photos I like how they added the metal tubing to make mounts for the tank. This is the exact tank I am using. A 87 blazer rank baffled for efi so I can use my stock fuel.pump and sender like my 91 engine ran. The green would be places to add square tubing supports...

Any ideas and tips appreciated. Thank you

[washington blue]

You have to have shocks, fuel lines, large exhaust pipes, springs, all in a tight space. I used a tank from POL with external pump, pressure regulator/filter, Just my choice, but there is no cutting crossmembers required and it's 19 gallons. Several other choices require no cutting of crossmembers as well.

[BBPanel]

Here is my 56 Panel w/25 gal Blazer tank. I wanted the tank to sit as high as possible so removed the expansion bubble on tank and welded in flat plate.

[_Ogre]

you need the x-member at the rear shackle mounts to keep the frame from flexing at the mounts
you have an x-member at rear and front spring mounts and at the front/rear cab brackets
i used a 20 gal tank similar to washing blue and needed to move the x-member back a few inches
so yes, you still need the rear x-member, moving it is a compromise, but you'll probably never haul a ton gravel
either move it back, i used 2x4 sq tubing going back in, but i also shortened my frame

shock bracket: again this doubles as a brace to keep the frame hump from flexing in/out
if it's not in your way just weld it up, if you need the space, weld in something in front of the axle
use either shock mounts, front or rear. i think they figured out that front leaning forward is better

[_Ogre]

bbpanel is not on springs, he can cut most bracing out as he's only supporting the body
a big freaking body, but a lot of air


and which ever way you choose, make sure you can remove the tank from under the truck
i have an in tank pump and needed to drop the tank three times for bad hose in the tank

[BBPanel]

Originally Posted by _Ogre

...i have an in tank pump and needed to drop the tank three times for bad hose in the tank

Hoping this will mitigate those issues but if not the tank will drop easily. May not want to do this with an open truck bed.

[Missyblue]

Originally Posted by washington blue

You have to have shocks, fuel lines, large exhaust pipes, springs, all in a tight space. I used a tank from POL with external pump, pressure regulator/filter, Just my choice, but there is no cutting crossmembers required and it's 19 gallons. Several other choices require no cutting of crossmembers as well.

Thank you for the photos. Those tanks are nice I just was struggling to justify a $400 and I orefered in tank pump so another $200 for that when I can run this 87 efi tank at $100 and intank pump at $50. But wasnt super excited to mess a bunch with the frame either. But the money savings helps me alot moving forward

[Missyblue]

Originally Posted by _Ogre

you need the x-member at the rear shackle mounts to keep the frame from flexing at the mounts
you have an x-member at rear and front spring mounts and at the front/rear cab brackets
i used a 20 gal tank similar to washing blue and needed to move the x-member back a few inches
so yes, you still need the rear x-member, moving it is a compromise, but you'll probably never haul a ton gravel
either move it back, i used 2x4 sq tubing going back in, but i also shortened my frame

shock bracket: again this doubles as a brace to keep the frame hump from flexing in/out
if it's not in your way just weld it up, if you need the space, weld in something in front of the axle
use either shock mounts, front or rear. i think they figured out that front leaning forward is better

Thank you for all the Info!! Yeah so I'm waiting on the tank to make sure but I potentially can leave the old shock crossmember. But the one for the leaf spring si thought I could cut the bottom off that hangs down and leave it across the top for some support in that area? Not sure if it's worth it but I could leave it. The tank will just shove up against it. I do plan on having straps to be able to drop the tank. That's would stink if I kept having to pull the bed

And yeah wont be hauling a ton of gravel that I know of haha.

[mr48chev]

If you put a new crossmember at the back there really isn't any reason to keep the old one or any part of it. It had that bump up in it to make room for the spare tire and it served no other purpose.

I have a length of 4x4 unistrut across the back of my frame installed just forward of the rear bumper bolt. I did that when I installed a 20 gallon aluminum auxillary gas tank that came with a camper van my mom had but was never installed in the van. The Unistrut came out of the scrap bin at work. I won't be using that tank in the rebuild though as it hangs down too far.

[_Ogre]

Originally Posted by Missyblue

And yeah wont be hauling a ton of gravel that I know of haha.

take pics if you do

i've seen people build a cradle to drop the tank into with the bare frame
the only way the tank is coming out is cut stuff or pull the bed. yikes!

[dsraven]

stock under frame tanks like the blazer had a set of straps front to rear above the tank and these fit the tank contour well, then a set under the tank to bring the tank up tight against the upper straps like a sandwich. no movement an well supported. easy to drop the tank. there was some webbing type material used as an insulator to help stop metal on metal contact. if you plan to cut out cross members first x brace the frame so nothing moves dimensionally. do it so the bracing will be out of your way if possible or so you can fab and install a new cross member or 2 and then remove the bracing to install the tank etc. like mentioned above, the frame has cross members for a reason so if you take one ouit you gotta figure how the frame will react if you change the location of the new one. also, like mentioned, try to figure out how all the systems will fit together in the same space to make it all work out, tank, fuel lines, shocks, exhaust, park brake cables, wiring, box mount hardware etc. it sucks if you have to remove a bunch of stuff to access other stuff. after years of fixing things I can't tell you how many times I have wanted to be face to face with the engineers who decided it was a good idea to install stuff on the frame and then install the body on top. a lot of the fasteners point the wrong way or are simply not accessible with the body on. try not to do that if you can. stuff like hose clamps that you can see but not get a screwdriver on, things like that.