I want to remove the tank from behind the seat, and put one under the bed, Any suggestions? I contacted Bobs f100 and for around 630. I'll have all with a 16 gallon polly tank, sending unit, brakets, and lid, but they say I'll have to move a cross member back. Does all this sound good, I've never done this before.

 

Sounds expensive to me. There are other options. Check the galleries of jniolon and Randy Jack (just to name a couple that stick out in my mind) to see some creative options.

Larger capacity tanks than what you have specified, for less money.

 

I got a plastic 18 gallon tank out of a 80-96 F-350 chassis cab. It will fit between the rails. I still need to put mine in.

 

I used a 25 gallon tank from a 78 Bronco. I had to change out my gas gage to match the sender and moving the rear crossmember was easy because you just flip it and attach it at the same frame holes. Mine is a 56, but the rear frame width is the same as yours. Total cost was under $200.



Here's my gallery on it: https://www.ford-trucks.com/user_gal...&albumid=24084

 

https://www.ford-trucks.com/article/...1953_F100.html

 

this was compiled awhile back, it has some good info;


Fuel tank FAQ

1948-1952 Trucks
The mid-1980s Chevy Blazer tank works well in this case and comes in both 24 U.S. gallon and 31 U.S. gallon capacities. At least one member of this FTE 1948-1960 Forum has successfully used this tank setup.
Another alternative is the 1970 Mustang tank with a 22 U.S. gallon capacity. Apparently, the earlier Mustang tanks discussed below will work on the 1948-1952 F-1/F-100s as well. Since the distance between the frame rails is nearly identical, anything that fits the 1953-1956 models should also fit the 1948-1952 models.
If you want a larger tank, the 1980 through 1986 (and possibly through 1989) full sized Ford Bronco tank is worth looking at. At 33 U.S. gallons capacity, it measures 31.875” long x 22.25” wide x 15.75” deep in steel, and slightly smaller in the polymer version.
Other tanks which have been used, but for which we have little info are from the 1980s GM Suburban and 1984-1985 Isuzu Trooper.
1953-1956 Trucks
Stock replacement tanks for the original locations are available in polymer or stainless steel from Tanks Inc. and several other sources – but since they are limited production they tend to be expensive.
No discussion of suitable fuel tank alternatives for this range of years would be complete without highlighting the early Ford Mustang tank (1965-1970). Forum member John Niolon has thoroughly documented this tank as a replacement in an article at http://www.clubfte.com/users/jniolo...mustangtank.htm (his web site has many other useful articles as well). The Mustang tank comes in three different capacities and all are easily obtained through www.gastanks.com or many Mustang oriented aftermarket suppliers. Another plus with this tank is that the Mustang sending unit will work fine with the stock 12v fuel gauge. A few minor nits however include 1) the inlet for filling the tank comes out the top at the rear, forcing you to bring it up through the bed 2) the filler pipe is approximately 0.75 inch off center towards the passenger side and 3) you may have to grind about a 0.5 inch off the bottom edge of your frame rails to fit the tank – although this is not a big deal. A lot of people have used this alternative, possibly more than any other single alternative.

Mustang Fuel Tank Installation


Yet another tank option is the full sized Chevy Van 1987-1995 fuel tank. It’s available in two different capacities – #GM8C (Spectra Premium Industries) has a 22 U.S. gallon capacity and a second version has a 33 U.S. gallon capacity. The difference between the two is the depth. The length and width are the same for both tanks. If you’re running fuel injection, you should be aware of the different system pressures that Ford and GM use. To avoid having to deal with this issue, with Ford engines use the non-EFI sending unit (#FG17A) and use an inline fuel pump. The 1990 Ford Ranger works well in this application. If you are running a GM power plant with EFI, then go the other way and use the EFI sending unit (#FG17B) which employs an in tank fuel pump and sending unit.


1987-1995 Full-Size Chevy Van Fuel Tank Installation
The 1977-1981 Chevy Van tank was offered in both 22 U.S. gallon capacity and a larger size as well. One of our FTE forum members (Tacson, AKA Donald Walker) has some excellent photos in his gallery which clearly show how well it fit and how he mounted it. The only difference between the newer tank used by Ferguson and the older model used by Walker is that the newer tank has the filler diagonally opposite the older tank. Walker used a slightly different mounting method – although both installations employed the original mounting straps for the tank.

1977-1981 Full-Size Chevy Van Fuel Tank Installation

Neither of the full-size Chevy van installations discussed above requires any cutting of the frame rails. However, both installations did require routing the filler tube through the frame rails.
The alternatives already listed provide ample, easily adapted, decent sized tanks. If you don’t mind admitting to using less cool sounding donors, then consider the following.
• The 1996-1999 Isuzu Trooper fuel tank – capacity unknown. There is a question about the availability of new sending units for this tank. However, at least one member of this forum has used it and there is an installation “how to” article in the June 1996 issue of Custom Classic Trucks.
• According to a few of our forum members, the 1961-1966 Ford Econoline Van tank is virtually identical to the early Mustang fuel tank – but the filler tube is on the driver’s side.
• Going back in time a little further, the 1957-1958 Ford passenger car fuel tank (Ford part# B7A9002B or www.gastanks.com part# F-34B) fits easily between the rails, holds 20 U.S. gallons, has a driver’s side filler, and can be purchased for about $200.
• Apparently the 1970 through 1977 Mavericks and Comets are similar to the Mustang tanks but the filler runs out the back.
• If you want to put the tank inside the frame and under the cab like the stock panel truck mounting location, an 1984 Ford Ranger supposedly works.
1957-1960 Trucks
Given the similarity in width of the rear frame rails for the 1957-1960 and 1948-1956 model years, anything listed for the earlier trucks should fit the 1957-1960 model years. Be aware, however, that no information on actual installations in the later year trucks is available at this time.
Classic Performance Products ( www.classicperform.com ) offers a tank that will fit under the bed of the 1957-1960 trucks. Again, since this is a limited production item, the cost is higher than a used tank would be. An alternative is an NOS 18 U.S. gallon tank, Ford part # COTB 9002-B available through Green Sales in Cincinnati, Ohio.
Fuel Tank Senders and Gages
A final consideration when using a newer or donor tank is compatibility of the sending unit with whatever gauges you plan to use. You may need to modify either the fuel sender or the fuel gage so that they have matching resistance characteristics. This can end up causing more grief than mounting the tank itself. The following information comes mainly from Autometer ( www.autometer.com ) and addresses the electrical characteristics of the OEM sending units.

Type of Sender/Gage Reading Empty (Ohms) Reading Full (Ohms)
Most pre-1965 GM 0 30
Some GM trucks through 1968 0 30
Most 1965 and later GM 0 90
Most pre-1987 Fords and most Mopar 16 158
Ford pre-1987 bi-metallic gauges 10 70
Ford 1987 and later F-series trucks magnetic gauges15 160
Note: Ford Motorsport gauges made by Autometer require the Autometer sending unit # 3262 which operates at 240 ohms empty and 33 ohms full unlike the normal Ford compatible senders as detailed above.


Here are a few more examples.

Randy Jack’s ’78 Bronco tank install (56 F100): https://www.ford-trucks.com/user_gal...4&albumid=24084

Tacson’s Chevy Van tank install (55 F 100): https://www.ford-trucks.com/user_gal...d=20494&width=0

John Niolon’s Mustang tank install (53 F100): http://www.clubfte.com/users/jniolo...mustangtank.htm

Ferguson777’s Chevy tank install (54 F100):
https://www.ford-trucks.com/user_gal...d=97344&width=0

bobbytnm’s Chevy tank install (49 F1):
https://www.ford-trucks.com/user_gal...d=79496&width=0

DennisB side fill Mustang tank: https://www.ford-trucks.com/user_gal...1&albumid=28273

Bobby

 

Thanks so much for your help. This gives me a lot to consider and go off of. Again thanks for your time!

 

will a 1979 ford f150 with dual gas tanks fit on a 1981 ford f150 with dual gas tanks? And how do u take the gas tanks off? What holds them on?