Velvet drive is one box that doesn't matter if it is turning or not. so seeing as fitting a shaft break is not so simple, allowing the box to spin freely is fine. It doesn't matter what
gear you are in as it is a Hydraulic box. If the front end of the box is nto turning, you have no
oil pressure and thus no cluthes engaged. So only the aft
gear is spinning. This is bathed in
oil so it is happy to spin freely.
Boxes that don't like being spun are usually because certain
parts are not bathed in oil and wear is a result.