The Air Release sound when you brake and come to a full stop does not work/play anymore for the URAL-4320 and M923A1. It's that 'psshhh' hissing sound after braking/coming to a halt.

The sound setup is found inside Vehicles_Ural4320_Animations.acp and Vehicles_M923A1_Animations.acp

Here's a video of what it should do like in older versions, and subsequently doesn't do currently.

An old 1.0 version:

Notice the hissing sound at the end after braking. This is not present anymore.