I've got a '91 EFI I-6 4x4 that has a hole in the fuel line from its rear tank. What size fuel line should I buy to replace it with? The shop manual mentions both 1/2" and 5/8" fuel line; I'm thinking 1/2" since the I6 isn't exactly a gas guzzler.

Second, while I was looking around trying to figure out why my truck pisses gas and doesn't start, I found a strange rubber hose on the rear brake system that's not connected to anything. It was dry rotted through and broke off the brake system when I bumped it. Here's some pictures:




Any ideas what that is and whether or not I should be worrying about replacing it?

 

That hose is the rear axle vent. You should replace it or you will get water and dirt into the axle housing.

I doubt the line is 5/8" but I'd measure it or simply remove it and match it up at your local parts store.