The Mirage kit is a very loose combination of parts that can make just about any variant of the Vickers - 7TP tanks; the molds are old as well, so there are going to be various fit problems. Not my first version of this kit - the only option is to mercilessly ben, heat, sand and glue until the hull is built.
Here's the 38(t) running gear mostly tacked on to the lower hull:
I removed the 7TP return rollers and filled the holes with sprue bits. The idler is missing because I thought I could modify the 7TP's idler wheel to match the width of the 38(t) tracks, and to match the drawing. The results weren't good. The wider wheel is OK, but just by luck, the gap between the spacer rods is just enough to grab onto the track's guide teeth. Also, there's no way of adjusting the track tension and I think I'll need to do that with this kit.
Instead, I went with the 38(t) return idler wheel, which gives a few mm worth of adjustment:
The Hobby Boss/ex-Tristar kit is really fantastic; the "working parts" are useful (like the idler wheel adjustment and the separate rubber tires for the road wheels) and the individual track links aren't advertised as being workable, but they click together nicely and firmly enough to make long runs that won't break. The suspension works as well (hence the weird wheel angles).
Here's a front/top view. I'll putty the hull and fix any obvious issues before I glue on the running gear:
