 This, combined with generally less wartime service than previous classes, led to the "Balao" and "Tench" classes being preferred for modernization programs and active postwar service.36 "Balao"s were modernized under various GUPPY conversion programs, plus 19 received the more austere "Fleet Snorkel" modernization, often in connection with foreign transfers.SS-361 through SS-364 were initially ordered as "Balao"-class, and were assigned hull numbers that fall in the middle of the range of numbers for the "Balao" class (SS-285 through SS-416 & SS-425–426).