yo Jeff,
Here is some info I have
"...Pre 90's have - 2" tank hole for a low pressure in-tank pump (feeds the high pressure pump) plus a high pressure frame rail pump;
Post 90- 3-5/8" tank hole for a single high pressure in-tank pump, no other pumps in the system..."
Source: by Dustin S
Installation Info, 19 gallon Polyethylene in a 78
Source: by 78broncoboy
"...
alright guys, i dont know if yall remember, but the 33 gallon tank hangs down real far , especially on stock suspension componets. i know, i know, get a lift, well, thats coming along shortly.
but to the point, i put a 19 gallon poly truck tank in my bronco, it wasnt real hard to do, pretty easy, in fact, if you have the right tools. basically you just cut out the rear most crossmember, shave off probally 3/8 to a half inch of steel on each lower frame rail edge, fab up a new rear most crossmember to accomodate straps, i just used a piece of U-channel that you can get from Home Depot, theres no good steel or scrap yards near the house. bolt that up, put the tank in.
i had to notch a good size piece of the upper frame rail for the filler neck hose to fit, but i reinforced the hole with a piece of 1/4 inch steel flat bar. go to NAPA, they have new fairly flexible filler neck hose for around 17 bucks a foot, part number NAPA #1055.
get that, cut it to fit, i just used my old vent hose, it wasnt that bad. put the tank up there, make sure it will fit. i used from fairly heavy guage galvanized steel straps that my dad found, but you could use any kind of thicker guage hanging strap for the bottom straps. the way the frame got cut, upper straps arent really neccesasy, but im gonna put them in anyway.
it could be a 2 hour job if someone had the right tools, and knew how to use them. i always bend and break saw-zall blades, so it took me longer, plus some of the drill bits i used sucks, which took even more time. but if you had a welder, for the fabbed up crossmember, and a good saw-zall, it wouldnt take long at all. a drill and bolts works fine, but takes slightly longer.
if you have ever popped a hole in a tank, and want something smaller, but cant find a 25 gallon sending unit like me, use the 19 gallon truck tank. it works fine, just be sure to have a couple jerry cans around..."
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