how big of a job is fixing fuel return hose. looks like there is already rubber hose comming off the back of pump. at least there is a stainless clamp on the hose at back of pump.

 

It's not too bad of a job, remove the fuel filter to access the engine end of the hose. Takes about 2' of 5/16" diesel rated hose.
Don't let the autoparts guy tell you all hose is diesel rated, most of it isn't.
If you're smart you should just abandon the stock system all the way from the tank to the engine. Takes about 12 feet but measure first.
Eliminates future problems and is easier than working behind the engine blind. The steel lines are well known to develop leaks, good hose will easily last the life of the truck.
Might as well replace the feed line at the same time, it's 3/8"

 

what he said. X2 do it once and pretty much be done with it. There will be plenty of other stuff to work on.

 

Thats what I did and it worked good! what he said x3

 

X4 I had many Fuel leaks. Go to a place that makes Hydrolic Hoses. They can sell you some real nice hose that will stand up to the Suction/ Costs about $8 a foot. But the Factory lines cost more at dealer and will just rot out again

 

$8/ft is pretty steep.
I pay less than $3/ft for some of the best marine grade fireproof diesel hose you can buy here> http://www.bluewatershipsstore.com/detail.aspx?ID=6891

The Trident #365 hose has walls at least twice as thick as the stock hose.

 

If you don't want to spend that much, go to you local car parts and get some of their "diesel rated hose" that will "work" for diesel I did about five years ago and just replaced it again last week. Buck something/foot, cost seven bucks (3' of each) and got enough 3/8" left to do another return (from engine/filter to metal lines). I'd go ahead and get new clamps.