I managed to get a copies of issues #69 and #70 of Combat Patrol which came with the sprues for a Goliath Rockgrinder.
Good value at £19.98 compared to the list price for the Goliath Rockgrinder which is £42.50.
I think though I will build this as a Goliath Truck rather than the Rockgrinder.
Infinitely adaptable, hard-wearing and rugged, the Goliath Truck is a mainstay of the Genestealer Cults. Fast and manoeuvrable, it bounces around the battlefield laying down walls of gunfire, heavy stubbers and autocannons ablaze. Once dedicated to the shadows, the crew manning the Goliath – proudly emblazoned with insignia of the Cult – now do everything in their power to get as close to the enemy, screaming rapidly across even the most hostile terrain to slam open their cargo compartment and disgorge broods of up to 10 scuttling Hybrids.
Though a Genestealer Cults vehicle I am guessing that it can be used by the Imperial Guard or other forces, as it is for intents and purposes an Imperial mining vehicle which has been commandeered by the cultists.
I am thinking of either painting it as an Imperial mining vehicle, in yellow; or I am thinking it might be a commandeered vehicle for use as a Chimera stand-in for some Tallarn Imperial Guard.