Cheap or not so cheap Suspension parts

Some time ago when getting a muffler replaced i was asked if i wanted the standard muffler at $39 with 1 year guarantee or the muffler with a lifetime guarantee for $129.Expecting the quality to be vastly different i asked how the mufflers differed. He thumbed through his parts book and fingered the $39 muffler and holding his finger on the number he found the lifetime warranty muffler and said with a big smile...what do you see? I looked at him, smiled back and said they are the same part number!