Everybody knows that a lot of GMC trucks have the problem with brake and fuel line rust over there along the frame above the fuel tank, especially if you live in a wet weather area. The local shop by-passed the rusted out section of my brake line on my 99 jimmy(same truck basically as the 99 blazer). Pretty easy for them, they do 50 to 100 of these rusty brake line bypasses a year. But the fuel lines can't be bypassed so easy. I believe to do the fuel lines right, you really have to drop the fuel tank. So I did. I didn't want aftermarket lines or patch kits for the fuel lines, so I paid $100 plus apiece for a new feed and a new return line from the GM dealer. Took me most of a full day, but I got it done. Actually, there's still 2 rusty emissions lines in that area that I'm going to repair someday with rubber fuel line. There's a total of 5 lines in that rust-prone area that run right along side each other...2 fuel lines, 1 brake line, and 2 emissions lines. See pictures of my feed and return fuel lines