In early days there were sub-types 'Dragon 11m (Basic)', 'A', 'B' and 'C', but during 1987 those in sub-types 'A' and 'B' were reconfigurated and reclassified into sub-types 'Basic' and 'C' respectively. Therefore sub-types 'A' and 'B' are void. A batch of buses in sub-type 'D' entered service during 1987-88. All these 221 buses were fitted with Duple Metsec body which is similar to those on 12-metre 3N4-191.

Forty-nine buses of sub-type 'E' joined the fleet in 1990-91. The Duple Metsec body was revised and is similar to those on the air-conditioned Dennis Dragons. Additional 100 buses which were classified as sub-types 'F' and 'G' were introduced in 1994. The chassis were originally designed for air-conditioning and the window frames were blackened.

Some features of buses of these sub-types are listed below. To view the photographs of them, please click on the hyperlinks to access the relevant pages, and click on the photographs on those pages for the enlarged version.

Sub-type	Vehicles	Number	Features
Basic	S3N1-55	55	Small louvres in the front dome when built Upper-deck seating 67 / Lower-deck seating 29 / Standing 55
C	S3N56-140	85	Large louvres in the front dome when built Improved ventilation Upper-deck seating 67 / Lower-deck seating 39 / Standing 31
D	S3N141-221	81	Upper-deck seating 67 / Lower-deck seating 41 / Standing 33
E	S3N222-270	49	Revised overall body design Fewer but wider spaced side windows
F	S3N271-319 and 370	50	No lower-deck rear window Black window frames First 25 powered by Gardner LG1200 engine
G	S3N320-369	50	Reduced opening parts of upper-deck windscreen