These sponsons came from the Storm Raven kit, originally armed with Hurricane Bolters. The guns were replaced with two Multi Meltas. The big problem I had was finding some sensors/camera for the turrets. I had no suitable vehicle bits in my spares box, and nothing useful elsewhere: that is, until I bought some Sicarian Ruststalkers for my Dark Skitarii at the weekend.
A possible addition to this tank is a Dozer Blade, or some sort of bladed apparatus, to the front. Once I've found a nice design I will begin work on it, then finish off the tracks and riveting.