Expanding VMDK in 6.5 with c#

I would like to expand a VMDK on a VM in our 6.5 environment via the c# Management SDK, and if I understand the documentation correctly the best way to do this would be to leverage HostExtendDisk_Task from HostVStorageObjectManager. The problem i'm having is how do I get the HostVStorageObjectManager object?  I have a feeling my method is close but I just can't figure it out Here is what i'm trying, but it is failing on a type conversion so it's definitely not correct. Do I need to get it from the VM host somehow?

HostVStorageObjectManager vDiskMan = (HostVStorageObjectManager)vimClient.GetView(vimClient.ServiceContent.VStorageObjectManager, null);

Any help is appreciated