The difference between the last batch of GWR box vans and the GER standard box van was actually just the angle of the head stock. GWR had a square end and the GER ones were tapered. there was a smaller GER version that was 15ft long. the GWR vans started at 15ft6 but the last batch of 1888, the same year as the first iron mink were built, were on the now standard 16ft under frame. Our GER kit also has the option of vents on the ends.   Marc