Expedition HQ (or part of the Group) are an SSM. I was told this by one of the owners. The Group needs to be to register the massive SLRV expedition vehicles they make. They also have a specific version of the Grenadier called the the Grenadier XSpec, which I have seen on some government database previously. I cannot remember where now. Their GVM kit goes to 3,800kg, not sure if they offer higher GVM, it may under the XSpec label but that is all offline, not on the website.
SLRV Expedition vehicles and Expedition HQ I believe are business names, the company name is something different and that will likely be the named SSM. I have an Invoice in the company name.
If anyone wants a GVM upgrade do your checks before deciding, regardless of who you choose.