They were devised by 12 Manitoba Dragoons while still in the UK in Februiary 1944, using two 12 foot lengths of No.9 track. They were then fitted to both 12 MD and to RCD Stags. It's described, and illustrated in my forthcoming "The Staghound in Canadian Service"
www.servicepub.com
here is a shot from the February, 1944 trials
Roger