I am wondering where I can find information about the Whippet's suspension.
I tried to find out how the rollers, drive- and idler wheels look like, but wasn't able to find a comprehensive source.
From the very few photos I could find of destroyed Whippets, I had the impression that the idler- and drive wheel looks the same as the ones of the Mark I, but can be totally wrong.
Maybe you should contact the curators of the IWM or Bovington, or the Army Museum at Brussels for that kind of technical information. BTW here's my work so far on the Emhar Whippet:
Photo 1: Thinning the track frame uprights to scale appareance. On the right, the original part as molded.
Photo 2: Scratchbuilt rollers visible under the track frame.