Some car owners will only go to the dealer for maintenance, while others are perfectly happy with an independent mechanic. The same thinking holds true in aviation when used airplanes are turned into freighters.
A Bulgarian air cargo company will soon start transporting packages for an express carrier with a 737-800 newly converted to carry containers instead of passengers after ditching Boeing (NYSE: BA) for a smaller engineering outfit to do the job.
Cargo Air canceled its order with Boeing...
https://www.freightwaves.com/news/freighter-conversions-boeing-or-the-other-guy