TOTO: what is the standard tankl for a CST743E bowl?

My toilet rebate program is very specific in spelling out the tank and bowl product codes. Often in an ad the EcoDrake II, for example, will say that it's a CST744, which is the number of the bowl, but it won't specify the number for the tank, so I wonder if that is standard, or do I have to buy them separately?

The Drake and Eco Drake
Bowls:
C743E, round
C744E, elongated
C744EL, ADA
Tanks:
ST743E, Watersense 1.28 gallon
ST743S, 1.60 gallon

The Drake II with double cyclone
Bowl:
C454CEFG
Tank:
ST454E, Watersense 1.28 gallon