My 68 F100 has 5/16 fuel line

 

If you're replacing your old fuel line hose then just clamp the old hose with a channel lock pliers or just blow the air back though the hose and break the siphon. Then just cut off a chunk of your old hose and go match it.

 

If your tank is behind the seat just take the metal line off the top of the tank!

 

Don't forget to take your gas cap off first.

 

so i took the fuelpump back to the place i bought it.i told them that i cant service it if i cant get the cannister off.i drew blank stares.finally i just went back to the shop and the guy was busy but if i wait he would get to it.quite a shop.lots of short blocks and a old sunnen hone.
then the goy put a oilfilter wrench on it in the vise-nothing.so he got the big channellocks and it finally broke loose.he just shook his head.

 

This style of fuel filter, built onto the fuel pump, make for good filterization of debris, and also collect any water that might be in the fuel.

Just replaced the fuel filter on my 390 FE, within the metal canister in the fuel pump. It was about -12 degrees farenheit wind chill factor. Hasn't warmed up much here, Highs in the 20's and 30's. Put a pair on channel locks to remove the metal canister and fuel filter. The fuel filter was stuck to the metal canister, the canister had about 1/4 level of water frozen at bottom. Had to pry out the filter.
The new fuel filter came with a new rubber o-ring to seal metal canister (Price $5.96).