here is how gm wants it done, click on images to see them, on a scale of 1-10 (10 is hardest) i would rate this job a 7. here are the instructions.
Fuel Tank Replacement (Single Tank)
J 43178 Fuel Line Disconnect Tool
Notice: Do not bend the fuel tank straps. Bending the fuel tank straps may damage the straps.
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Tighten Tighten the nuts to 10 N·m (89 lb in).
Tighten Tighten the bolts to 40 N·m (30 lb ft).
Tighten Tighten the clamps to 2.5 N·m (22 lb in).
Fuel Sender Assembly Replacement
J 44402 Fuel Tank Sending Unit Wrench
Important: The fuel pump strainer must be in a horizontal position when the sending unit is installed in the tank. When installing the sending unit, assure that the fuel pump strainer does not block full travel of the float arm.
Align the alignment tab to the correct location on the fuel tank.
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