Open sheep wagon C is a freelance 4 plank wagon with a loading ramp. This version has a flat base that can be mounted on the Peco GR- 300 flatbed wagon. There is also a version with its own chassis built in to suit 6mm N gauge wheels. See some of my other models on my blog at http://modelengineworks.blogspot.co.uk
Base dimensions are 23mm width x 42mm, Length.