Interarms Mark X Mausers came in several different finishes: the Viscount (no forend cap/pistol grip cap, two-stage trigger, brownish satin varnish finish), and Marquis (forend cap, pg cap, adjustable trigger, sling swivel studs, varnish finish), and Whitworth later in production (forend and pg cap, adjustable trigger, sling swivels, oil finish look, although I am sure it was a sprayed varnish of some sort). Some of the Whitworth rifles came with an unusual stock, had a piece of harder wood laminated in right down the middle. Mark X Marquis rifles also came as a Mannlicher with a steel forend cap and nicely finished. All in all, Mark X rifles were pretty nice, even compared with Winchesters, Rugers, and Remingtons. And they usually shot very nice.
Towards the end they got pretty cheesy, the stocks were made out of some kind of hardwood and painted or dipped for camo effect. By then Interarms was having troubles, so they cut corners where they could.
Interarms had offices in England, so they stamped their firearms "Manchester, England", Interams logo, then "Alexandria, Virginia" at least through the late 1980s.