fli-lite skis

[heavylift]

I was skipping through the photo album and came across fli-lite hydraulic skis.Photo# 623 Now, I own a pair of skis just like those, But they bolt on.
No hydraulic stuff. Question: Is the hydraulic system added on, or did these skis come as is. I would really like to modify mine. Anyones got some info would be much appreciated.
Cheers.

[Cubus Maximus]

I don't know much about the history of these ski's. The ones in the picture came with the airplane when a friend bought it. They're a pain to take on or off but the hydraulicly operated plate that slips under the wheel seems to be an original part of the skis. (about 50 wobbles of the hydraulic pump handle moves both plates into position.)