Looked through my stuff and sales brochures for HJ commercials don't refer to Belmont, just Holden ute and panelvan (and kingswood ute), and no belmont badges visible. No smoking gun to be found there to support Belmont in early HJ commercials.

But I did find a newspaper sales ad 30/1/75 (placed by General Motors-Holdens Sales Pty Ltd) listing revised prices for the complete Holden range after Federal Tax cuts(Torana, Statesman included- sorry Byron, sort of understand your point on the subject- but always be all Holdens to me). Included in list as far as commercials go is Belmont Panelvan, Belmont Utility, Kingswood Utility, One tonner.

Incidentally the Belmont badges on the ute I have (and who would voluntarily put them on if they didn't come originally??) are on the guards behind the front wheels in the location that the kingswood badges are in HJ.