SSG
In 1970 an anti-terrorist role was added. This mission was given to the Musa Company, an independent formation within SSG. The name was given after the name of Prophet Musa (Moses). The company was originally formed in 1970 as a combat diver unit. In 1980 however each company was given a diver unit. After the Musa company was converted to an anti-terrorist unit, it received training by British SAS advisors in Cherat during mid-1981.
Just stumbled upon this thread by chance today, and wanted to point out the Musa Coy was raised as Amphibious Ops and never had the AT/CT role. The history quoted on the internet is incorrect and usually traces back to a commentary published in ICT or to dead links.
Musa Company since it's raising day has been an Amphibious Ops Specialist, and later raised SSG-N.
Source: Company History Book
The AT/CT role was being performed by 3 Cdo Bn in the 1970s/1980s during which era the bn was specialized in Hostage Rescue Ops (Pan Am Flight 73, 1986 being the most popular). To this day, 3 Cdo Bn has the highest number of Shaheeds and War Wounded personnel, the number being approximately 3 times higher than other Bn, owing to their operational activities in KPK and Balochistan as far back as mid-1970s.
Later in the late 90s - early 2Ks, 4,5, and 6 were raised along with Zarrar and Karrar Coys (specialized in CT, inheriting the role from 3 Cdo) which later on became Z.A.T.U. (Zarrar Anti Terrorist Unit) - this was the period under Gen. Musharraf when SSG gained the status of a Div.
And then during early years of WoT, 7 was raised along with S.O.C.U. (Special Operations and Communications Unit).
8 was raised as recent as ~ 2014/5 (though I'm forgetting the exact year)