D.R.F.15 Posted September 10, 2016 Report Share Posted September 10, 2016 Hey guys, I was wondering what would be a good replacement for the gas tank on a 620? I was thinking of getting a fuel cell installed, since the original tank is beat up, but if there is a less expensive option then I can go that route. Quote Link to comment
datzenmike Posted September 11, 2016 Report Share Posted September 11, 2016 A new tank would be cheaper or fix the old one..... and they fit. '78 and '79 of your model are the same and bolt to the frame. Earlier ones bolt to the box. A fuel cell won't run any better. Quote Link to comment
D.R.F.15 Posted September 11, 2016 Author Report Share Posted September 11, 2016 yeah that's what I was thinking. it's honestly not about it running any better per se, but the gas tank is real old. Ill keep it in mind though, thanks Quote Link to comment
datzenmike Posted September 11, 2016 Report Share Posted September 11, 2016 I'm old but still get up and put 8 hours in every day. Old isn't a good enough reason for replacing unless tires. Spend time/money on more important things. 1 Quote Link to comment
darrel Posted September 11, 2016 Report Share Posted September 11, 2016 '78 and '79 620 gas tanks are different. I had to replace the one in a '78 I had and picked one out of a '79. Both were king cabs. I'm not sure of the differences as I had someone else do the work. They had a '78 620 and took the tank out of that. So I do have a '79 kc tank with a repaired dent available. Quote Link to comment
racerx Posted September 11, 2016 Report Share Posted September 11, 2016 If it aint why fix it Quote Link to comment
datzenmike Posted September 11, 2016 Report Share Posted September 11, 2016 Reg cab short wheelbase and King Cab trucks use the same tank '78-'79.17201-B9800. 50 liters (11 US gal) Reg cab, long wheelbase are 'longer' tanks 17201-B9860 but still the '78-'79 still applies. 64 liters (14 US gal) This tank would extend forward under the cab if used on a long wheelbase King Cab... it can't, the front top of the tank does not clear the cab. Later 720 trucks have a notch in the top of the tank for clearance. 1 Quote Link to comment
Charlie69 Posted September 11, 2016 Report Share Posted September 11, 2016 1980 720 regular cab is the same tank. Quote Link to comment
Jersey Posted September 12, 2016 Report Share Posted September 12, 2016 Reg cab short wheelbase and King Cab trucks use the same tank '78-'79.17201-B9800. 50 liters (11 US gal) Reg cab, long wheelbase are 'longer' tanks 17201-B9860 but still the '78-'79 still applies. 64 liters (14 US gal) This tank would extend forward under the cab if used on a long wheelbase King Cab... it can't, the front top of the tank does not clear the cab. Later 720 trucks have a notch in the top of the tank for clearance. If the '78 has a build date prior to Jan '78 than it is the bed mounted type of tank, frame mount is Jan '78 and on. My buddy has a '78 with a build date of 11/77 and the tank is a bed mount. He does, however, have disc brakes. 1 Quote Link to comment
datzenmike Posted September 12, 2016 Report Share Posted September 12, 2016 Correct. Half way through the '78 model year went to frame mount. Thanks Jersey 1980 720 regular cab is the same tank. They may very well interchange, but way different part numbers, Charlie. The '80 to mid '82 2wd and 4x4 gas tanks were the same for reg and long frame trucks. Same capacity as the 620 still. 2 Quote Link to comment
Charlie69 Posted September 12, 2016 Report Share Posted September 12, 2016 I have compared them side by side and they are the same tank. The sending units are a little different but can be inter changed. Mike the part numbers for the 1980 720 upper control arms are different part numbers then the 1985-86 part numbers but they are identical parts. Quote Link to comment
Jersey Posted September 12, 2016 Report Share Posted September 12, 2016 Correct. Half way through the '78 model year went to frame mount. Thanks Jersey You're welcome Mike Quote Link to comment
datzenmike Posted September 12, 2016 Report Share Posted September 12, 2016 I have compared them side by side and they are the same tank. The sending units are a little different but can be inter changed. Mike the part numbers for the 1980 720 upper control arms are different part numbers then the 1985-86 part numbers but they are identical parts. My info shows RH 2wd 720 upper as 54533-01W00 up to 10 '82.... 11 '82 and on, is a superseded number 54533-25W00. If you ask for the old number the new one is also shown. My guess is some manufacturing process was changed or maybe the maker/supplier, something not obvious. Maybe the part was hardened differently? Different metal alloy? Same with the tank. Quote Link to comment
Jester Posted September 26, 2016 Report Share Posted September 26, 2016 Has anyone played with the tanks from a newer truck with efi? A factory in tank fuel pump would be nice. Especially when one is thinking of an engine swap. Asking because I need a new tank and am trying to think ahead a little. Quote Link to comment
hobospyder Posted September 26, 2016 Report Share Posted September 26, 2016 I've been debating in fabbing a tank to sit in the factory spot. Project binky style but haven't gotten there yet Quote Link to comment
datzenmike Posted September 26, 2016 Report Share Posted September 26, 2016 EFI fuel pumps put out 10X the pressure. You could try a new tank but keep the mechanical pump till you get the new EFI engine. Quote Link to comment
Z-train Posted September 27, 2016 Report Share Posted September 27, 2016 EFI fuel pumps put out 10X the pressure. You could try a new tank but keep the mechanical pump till you get the new EFI engine.Just reg it down. Quote Link to comment
datzenmike Posted September 27, 2016 Report Share Posted September 27, 2016 You could, but that's just adding something not totally necessary. You have the stock pump, already there, and it works perfectly for the 620. Easier to run what ya brung and when swapping to EFI the other pump is waiting. Quote Link to comment
willz Posted October 5, 2016 Report Share Posted October 5, 2016 Frame mount fuel cell isn't super easy or cost effective. Ask me how I know Quote Link to comment
Goemon Posted September 20, 2021 Report Share Posted September 20, 2021 A 720 tank will fit 78-79 620, Standard or KC and the Longbed tank will work. You just have to cut off the nuts or drill them out in the front of the tank. Bolt pattern is the same. That is the 720 rear hanger, almost the same as 620 2 Quote Link to comment
Yowakawaka Posted July 9, 2023 Report Share Posted July 9, 2023 @Goemon What year 720 tank did you use? I red one for a 79 620 and can’t ind one anywhere. Quote Link to comment
datzenmike Posted July 9, 2023 Report Share Posted July 9, 2023 That looks like a short wheelbase regular cab tank. If you have a long wheelbase King Cab 720, the tank is longer has a notch at the top front for clearance. The Long Box tank (with regular cab) is also longer but does not need the notch. It's also the highest capacity tank. Quote Link to comment
Yowakawaka Posted July 11, 2023 Report Share Posted July 11, 2023 @datzenmike I’m sorry. What year 720 tank do I look for if I have a 79 620? Quote Link to comment
datzenmike Posted July 11, 2023 Report Share Posted July 11, 2023 2 and 4wd regular cab short wheelbase 720 through '82 should work. Quote Link to comment
EDM620 Posted July 12, 2023 Report Share Posted July 12, 2023 4wd tanks are a bit deeper and have slightly more capacity. Quote Link to comment
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