Here is a sheet of 8 stamps from Dhufar one of which shows the regiment, bottom right). The stamps relate to the Royal Wedding of 1973 between HRH The Princess Royal and Captain Mark Phillips.
Stamps from Dhufar and the State of Oman were issued by exiled Imam Ghalib bin Ali al-Hinai’s Oman Imamate State, a rebel group against the Sultanate of Oman. The exiled government was attempting to establish an independent area in the north of Oman, and printing their own postage stamps would reinforce their independence. Although very few of their stamps were used postally many different issues were printed as collectors items especially for topical collectors. In fact, most sheets had the cancellations printed during the lithograph process and not applied after the stamps were printed.