Here are files for a BR built Mackerel ballast hopper drawn full size so scale to suit your model.
They were developments of the earlier Trout hopper but have a slightly longer wheelbase and body and less capacity. They also had a vacuum brake.
Versions with plate and split axleboxes have been drawn.
Appropriate buffers can be found elsewhere in my designs.
Bespoke transfers have been created for this model and are available from Cambridge Custom Transfers.
Enjoy
Jonny
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