This is a A-21A853 Spark Plug PN: 21A853Main Description As Following : A-21A853 Spark Plug P.N: 21A853 Dim A (1): Champion D21Quantity: 6Thread: 18mm Replaces: D21 MISCELLANEOUS , Crossed From: M10AC0 BOSCH , 5612032 GMC HOUSINGS Found in Section & Models : Ignition & Electrical Parts > Ignition & Related Parts, Case-IH TRACTOR: SEVERAL, Case-IH TRACTOR: 560, Sunbelt - Electrical > Spark Plugs, Champion (UNDEFINED): SEVERAL Associated Items : New Also A-MNL18344, A-IH-C-MUSCLES, A-IH-O-4602PT, A-IH-P-ACCESSORY, A-IH-P-RMDSLPUMP, A-IH-P-560660, A-IH-PM-460ETC, A-IH-S-BRAKEREP, A-IH-S-CARBSPEC, A-IH-S-CLUTCH, A-IH-S-ELECDIA, A-IH-S-ENG460ETC, A-IH-S-LPG460, A-IH-S-PUMPD236, A-IH-S-TOOLSLATE, A-IH-S-TUNEUP, A-IH-S-140EL, A-IH-S-460560, A-SMIH25 And : Champion D21 Dim A (1): Champion D21 Quantity: 6 Thread: 18mm