There are several hush kits for the 727.
Allthough technically not a hush kit one of the most popular options for owners is to replace the two outboard motors with the same engines that power the MD-80. As part of this conversion the center engine thrust reverser is removed and replaced with a mixing baffle. The more powerfull JT8-200 engines make up for the lost of center engine thrust caused by the mixing baffle. They also allow for a lower engine thrust setting so the motors are less noisy.
The Northern Aircargo 727 on the top is not hush kitted.
The Corperate 727 on the bottom has the MD-80 engine conversion. Also it is sporting the Valsan winglet modifacation too. Sorry for the far away shot.
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