But the Alvand class, as edlivered to Iran, had 1 × 3 barrelled Anti Submarine Mortar Mark 10 Limbo launcher. The firing of the Mortar Mk 10 was controlled by the British Type 170 (and later the Type 502) narrow beam attack sonar and Type 174, a medium range search sonars (giving slant range). They were refitted in the UK shortly before the 1979 Iranian Revolution. At which point 2 × triple 12.75 in (324 mm) torpedo tubes were installed and the Limbo mortar removed (and sonar likely changed).
Limbo is between Sea Killer launcher and stern gun.
Here 324mm torpedo tubes have replaces the Limbo mortar