Eureka Miniatures has new French Revolution Horse-drawn Artillery and Limbers available over in their webshop.
From the website:
We have both four and six horse teams available in walking and running poses as well as separate limbers. All limber teams were crewed by civilians, something which did cause problems at the time as the spirit of the drivers did not always match that of the gunners.
All of these items can be also be used with our previously released foot artillery figures.