Sisu S-321, S-322 and S-323 is the first lorry and bus model series made by the Finnish heavy vehicle producer Suomen Autoteollisuus (SAT) in 1932–1934. Upgraded models S-341 and S-342 were produced in 1934. The vehicles were heavily based on Volvo components. The two-axle, 4×2-driven lorries were designated with 2 500 kg capacity and total weight of 4 800 kg.The series was followed by the 1934 introduced Sisu SO-models.