I have inherited my parents 1977 f250 the fuel with a cab tank and two side tanks. Along the way the tanks had been removed and cleaned but when they were reinstalled all the hoses were removed. I can't seem to find a hose diagram so that I can put it back to original, any help would be appreciated

 

The trucks never came from the factory with three tanks. Factory installations, at most, came with two tanks.
If your in-cab tank is factory, your truck should be an early '77 4WD (AKA "Highboy"). If that's the case then, more than likely, the two under bed tanks are aftermarket.
Is the valve that switches the tanks manual? The factory unit was electric.
Here is the only thing that the '77 shop manual shows for line routing on the dual tanks. I enlarged the section that shows the valve.

 

The truck was a special order from the factory with 3 tanks, My parents intended to long haul a fifth wheel. it has a manual valve in the cab and a electric valve under the truck,

 

My 77F350 was ordered as a cab and chassis. It came with the behind the seat tank. the Original owner made a custom welding bed with a built in tank. He also plumbed it to be able to run the fuel out of the welder so it essentially had 3 tanks. It has a manual valve on the floorboard by the door. Not sure if any of this helped or not but it shouldnt be that hard to make something work.

 

Not sure if this is how your truck was originally set up but this is how I would do it.
On the electric valve; line "A" goes to the engine. Line "C" goes to the in-cab tank. Line "B" goes to the outlet of the manual valve.
On the manual valve there should be three ports. The outlet port goes to the "B" port on the electric valve. The two inlet ports go to the two under bed mounted tanks.
In operation, with the electric valve set on "main" you should be running off the in-cab tank. With the valve set on "aux" you should be running off of whichever under bed tank you've selected.

 

After talking with a gentleman that had retired from a dealership here he explained that the cab and bed option was only for the camper specials. There is a 3 way splitter by the solenoid valve that allows you to also to use the cab tank option. He was correct its there so now its just a matter of figuring what's in and what's out configuration. Thanks to all that helped