yes it is safe, you can run biodiesel in any diesel engine with little to no modifications. i have the same year truck as you and run bio w/o problems. biodiesel will clean out your fuel tank and fuel system and all the deposits will get cought in you fuel filters. depending on how dirty things are (miles on truck and quality of previous fuel) you might want to change you filters after the fist couple tanks. b20 will not clean it out as fast as b100 but overtime it does its thing. my truck runs better on bio, the engine idles smoother and really quites down.
ford warrentys b5 maximum. so you tequnically could have issues. i took my truck in once and was running close to b100, they techs noticed and thought i was running straight kitchen grease and tripped out but they said to just bring the truck back with diesel it in. i was having turbo problems so it wasn't the fuel. remember that they don't warrenty fuel related problems anyways, so if you got some bad diesel they would say take it up with your fuel supplier.
Next question.....Is it safe to run in my '05 with no modifications to the engine? I dont know much about this stuff.
Check your owners manual. I believe the engine warranty is a max of B5 or 5% biodiesel from a commercial source. All i do is some math and I can get it fairly close by supplementing the bio with additional fuel.
In the Des Moines area we blend a alot of different percentages. I don't know what Sapp Bros are doing, but the manager will know the percentage blend. In the winter time the majority of the customers cut back to B-5 for ease of handling and customer problems. Summer time you will see alot of different blends depending on the price spread between No.2 and B100. Check the Pilot in Council Bluffs, I think they have a dedicated tank to B100. Hope this can help.
They sell B-5 bio at the Lucky gas station in Plattsmouth. Head south into Plattsmouth on 75 and go past Tincher(car Dealership). On the right hand side at the stop lights is the gas station, right in front of Plattsmouth Keno. Also Terror Free Oil on 132 and Q sells bio but I don't know what mix it is. Terror Free is on the South side of Q street, right next to QT. Hope this helps!