One thing that's deep in the old fluff for Genestealer Cults is Limos. As an idea they really encapsulate the Oldhammer style of these armies. I held out for what seems like ages for good models that capture that ethos but can also practically play the part of a Chimera-stand-in. And here they are, played by the Patriot Armoured Carrier from the Dystopian Legions range, in WIP state.
This set of models sent me wild the first time I saw them previewed around a year or so ago. I'm very pleased with the two that I've picked up - the resin detailing is fantastic and they fit together really nicely. As you might have noticed, I've made a couple of changes to bring them into the 40K universe; namely, the addition of heavy bolters on the turret and at the front. A simple change that brings them squarely into the role of Chimera proxies (they are roughly the same size, albeit slightly narrower). All this detail is a joy to paint too. I should also mention that these actually work out as marginally cheaper than the GW models. A nice little bonus.