The 2006 GMC W3500 has two recalls, the more serious being a fuel tank that can corrode and leak fuel, creating a fire risk if the leak reaches an ignition source.
The second recall involves an engine oil pipe bolt that may not have been properly tightened at assembly. Over time, the bolt can work loose and allow oil to seep or leak from the seals where the lubrication pipe connects to the vacuum pump. Left unaddressed, an oil leak in the engine bay can create its own fire hazard and lead to oil pressure loss.