The convicts are Md Masud, 36, son of Abu Tareque, and Mostafa Kamal, 32, son of late Bissad Sarder, hailing from Rajshahi.
According to the prosecution, a team of Shibganj Police Station searched a truck at Koylabari Truck Terminal in Shahbajpur union and recovered four pistols, eight magazines and 731 bottles of Phensedyl syrup on April 23, 2013.
Later, police arrested Masud and Kamal in connection with the recovery.
Golam Rasul, sub-inspector of the police station, filed two cases -- one under the Arms Act and another under the Narcotics Control Act -- against seven people, including the duo.
Police submitted a charge-sheet against them on June 30, 2016.
After examining all the records and witnesses, Judge Shawkat Ali of the Special Tribunal-2 handed down the verdict acquitting five other accused.