Not a Carroballista ... it's a limber

 

It just seems to me to be a logical choice when moving artillery over longer distances. If I recall, a Scorpio (being relatively light) can be man-handled to some extent in Hail Caesar but I reckon if you really wanted to shift them, it calls for a mule cart.

The same way I play later period artillery, when a battery moves the artillery pieces come off and the limber model goes down. If you look closely you may notice I still haven't painted the reins I made from bottle-foil.

 

I bought another scorpio and fixed it in the back (nice fit as luck had it) together with the bolt-tub and I added styrene rods for the windlass.

I love a good mule and it was fun painting particularly 'muley' colour schemes for them.