Fuel tank vent hose replacement?

[2500diesel]

I'm replacing all of the fuel system hoses on my '82fi. I figure 32+ years is enough to ask of a piece of rubber.
At the top of the fuel tank are 3 black hoses going to a small round round fitting, then a clear ( well, at some point, it was clear. . . .) hose marked Cavis which runs through the bulkhead to a hard line. I assume that's a vent hose.
My question for the tifosi here: why three hoses, and can I just cap two and run a new clear hose through the bulkhead to the hard line?

[sptcoupe]

You can cap two.
I have just replaced the hoses and tank and fuel pump/filter on the coupe, and have not been able to find a replacement for the "clear" vent hose. I has a 5/8" ID and a 3/4" OD. If the OD is any larger, you won't be able to get it through the hole in the metal structure it runs through or bend it to fit onto the tank outlet. Let me know if you come up with something that works with the new gas and fits!

[2500diesel]

I'm sure the hose in my spider is much thinner than 5/8 id. My hose says 7x12 (I assume mm). Wait, I'm looking at a photo, yeah, you're talking about the hose from tank to fuel filler cap assembly. Mine says 14x21. Bevel Heaven (for old Ducati's), carries Cavis Benz fuel hose in 7x12, but it ain't cheap!

[sptcoupe]

Yep - that's the hose. Thanks for the tip. I'll be checking them out. Fortunately, it is a short hose!

[kgfiske]

Auto Ricambi sells both the CAVIS brand 14x21mm overflow and 7x12mm vent hoses (in the fuel section), but these hoses are not cheap! Midwest Bayless sells the 7x12mm CAVIS vent hose as well.