Regarding the Typhoon 60, these were the 4th offering in the Enya line. First engine was a 3 bolt 19 from 1950, then the 29 Typhoon in '52 followed by the 6 bolt Typhoon 63 in about late '53 then the Typhoon 60 in 1964. The 60 and 63 were identical apart from bore size and were also the only Enyas to have serial numbers with the 63 being numbered from 6000 (less than 1000 made) and the 60 was numbered from 7000 with about 5000 made. Production finished in about 1968.