brake line replacement; '90 GC

The left side brake line has rusted through near the gas tank on my '90 GC. I see a strange looking manifold about midway along the chassis where there are two brake lines in and two out. It also has a turn buckle looking thing attached. I would just splice in to the tubing, but the spiral reinforcement over the tubing has rusted itself to the tubing, which makes connections and Tees difficult. Then I thought about starting at this manifold, but it intimidates me. Anyone got any ideas?