A system and method for assembling a fuel tank is disclosed. A measuring device is mounted on a carriage on which at least one machine tool (e.g., saw, router) is also mounted. This carriage is operatively interconnected with a computer and may be longitudinally moved between a headstock and tailstock which are longitudinally displaced and on which various subassemblies of the fuel tank may be mounted during the assembly of a given fuel tank. Length measurements are preferably made of each fuel tank subassembly prior to any machining operation being executed thereon, as well as after each such machining operation, by monitoring/knowing the longitudinal position of the carriage via the measuring device. These length measurements may be automatically recorded on an appropriate computer-readable storage medium in relation to the subject fuel tank subassembly and the subject fuel tank. This information may be used to evaluate supplier compliance with engineering specifications and/or performance of the system in assembling fuel tanks.