All of the Drakes, which are G-Max will have S in the model number
You would be looking at the last letters.
D- Insulated tank
B- Bolt down lid (I've never seen one, this would be to prevent vandalism)
L- ADA 16.5" high bowl
R- Right hand tank lever(Used mainly for handicap stalls where the trip lever needs to be on the access side)
Most tanks come with left hand levers.
Other models can have
F- 16.125" high bowl
CST743S, 14.5" high regular bowl Drake
CST744S, 14.5" high elongated bowl Drake
CST744SL, 16.5" high ADA elongated bowl Drake
CST744SD, insulated tank
CST744SDB, insulated tank, bolt down lid
CST744SR, right hand tank lever