My 10.25 was open.
The clutches wear out too, so expect at least that.

Don't just think they are limited slip, look at the axle tag for an 'L' where the '.' would be in the ratio.
i.e. 4L10 XXX instead of 4.10 XXX

The service body definitely looks C&C.
There are no flares over the wheels like a pickup.
Maybe the body is that much wider than the cab.