ToiletFitGuide

TOTO Drake ST743S and ST743E both use flapper THU500S and fill valve TSU708

Last updated: 2026-10-27

Both Drake tanks (ST743S, 1.6 gpf, and ST743E, 1.28 gpf) use flapper THU500S, fill valve TSU708 and flush tower THU440-A.

They differ in the drain valve (THU443.10B-A vs THU445.10F-A) and the tank lid (TCU743CR vs TCU743CRE).

Sources: TOTO CST743S parts manual, TOTO CST743E parts manual.

TOTO parts by tank

Part (TOTO's words)ST743S (1.6 gpf, G-MAX)ST743E (1.28 gpf, E-MAX)
Flapper w/ ChainTHU500STHU500S
Fill ValveTSU708TSU708
Drain Valve for Tower TypeTHU443.10B-ATHU445.10F-A
Flush TowerTHU440-ATHU440-A
Tank Lid (Cotton)TCU743CR#01TCU743CRE#01
Trip Lever (Cotton)THU068#01THU068#01
Seal Gasket (1 piece)THU407THU407
3" Tank to Bowl Gasket9BU024E9BU024E
Tank Mounting KitTSU01DTSU01D

Sources: PD-00237 v.10, Dec 2021, PD-00130. Color codes: #01 Cotton, #03 Bone, #11 Colonial White, #12 Sedona Beige, #51 Ebony.

S or E tank

Check the tank number inside the tank; see find your tank number. The S manual is for a 1.6 gpf round toilet; the E manual for 1.28 gpf.

See Kohler canister seal or flapper size.

Sources

  1. TOTO, Parts Manual CST743S Drake 1.6 gpf (PD-00237 v.10, Dec 2021): https://www.totousa.com/filemanager_uploads/product_assets/PartsManual/PD-00237_CST743S.pdf (read 2026-10-27)
  2. TOTO, Parts Manual CST743E Drake 1.28 gpf (PD-00130): https://www.totousa.com/filemanager_uploads/product_assets/PartsManual/PD-00130_CST743E.pdf (read 2026-10-27)

Last checked 2026-10-27.