When I first saw the pics I has a feeling this would be a 2 in 1 kit. The sprue pics confirmed this for me. What does this mean – well in a nutshell you can build both turrets independently without duplication of parts. The tank front panel and side armour are simply cosmetic and easily explained away by different chapter appearances, so essentially if you have a magnetised tank or spare rhino you can use one of the as a spare hull to mount your other turret on! Note the one part not redundant is the small antennae array - I mounted it on the hunter as it doesn't get missed on the stalker. I used a couple of BA/DA tanks for the pics as I haven't had the chance to assemble the hulls for them yet.
I assembled the turrets, magnetising the icarus stormcannon so it could pivot easier (see pic). Other than this all you need is a pair of rhino hulls (one comes with the kit obviously) with the doors, lights, front armour and top hatch removed. In any mixed combo, you have all the parts for one tank already in the kit. For the second I used a black templar rhino front (though any GW/FW one will do), the extra side armour from the vindicator kit and a couple of pieces of plasticard to proxy. If built in the right way with magnets, the hulls can be used as other tanks as well. Better still, the two armies these chaps are joining are Iron Hands and Black Templars, so I can still interchange the turrets between them as they’re both going to be black.
There you have it. Hope this is of help to people. Cheers.