Not very helpfuf answer possibly as the stabiliser legs are difficult to impossible to get out of the guides - the latter in my case. Having said that, it is quite likely they are interchangeable as this would be typical of Playmobil.
Height = 56mm; top is circular with a flattened edge which coincides with a broad slot running down the leg. The leg does not have a true thread, but a series of raised ridges. Not being able to get the leg out, I counted the raised ridges as well as I could and it looks like there are 7. The foot is 24mm by 23mm, and is not square in shape, being indented on two sides.
Hope this helps.