Back towards the beginning of July crew sizes were increased as follows (from what I remember)
Engines from 6>10
Rescues 4>6
Trucks 3>6
Rescue Engines/Quints 6>10
I understand that they were removed due to people having issues with how they were implemented (Vehicle crews). If there was a way for them to be re-implemented so that pre-existing apparatus wouldn't be affected by default there shouldn't be as many issues.